[AggressiveInstCombine] Add logical shift right instr to `TruncInstCombine` DAG

[anton-afanasyev]

Summary

Add lshr instruction to the DAG post-dominated by trunc, allowing
TruncInstCombine to reduce bitwidth of expressions containing
these instructions.

We should be shifting by less than the target bitwidth.
Also it is sufficient to require that all truncated bits
of the value-to-be-shifted are zeros: https://alive2.llvm.org/ce/z/_LytbB

Alive2 variable-length proof:
https://godbolt.org/z/1srE1aqzf => s/32/8/ => https://alive2.llvm.org/ce/z/StwPia

Part of https://reviews.llvm.org/D107766

[lebedev.ri]

We don't actually need *all* the high bits to be zeros,
only the ones that would be potentially shifted-in,
iff we don't truncate them away first.
E.g.: 0b11100111, target bit width of 4, and shift amount of 0..1: https://alive2.llvm.org/ce/z/jJ85EE

But indeed, we only have the 'min' bitwidth, we can't really model that here,
especially because 'max' bitwidth would differ for different 'min' bitwidths...

So LG, i guess.
@spatel ?

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

293

[anton-afanasyev]

We don't actually need *all* the high bits to be zeros,
only the ones that would be potentially shifted-in,

Sure, that's why it's only sufficient condition, not necessary one. Hope it's the most common case in real life.

[anton-afanasyev]

Rebase after shl bugfix

[spatel]

In D108201#2951907, @anton-afanasyev wrote:

Rebase after shl bugfix

Add tests similar to 0988488ed461 (multiple widths) and 803270c0c691 (64-bit) for lshr patterns?

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

295–296

This wasn't updated with the suggested change to use getActiveBits().
IIUC, we can make this more efficient (avoid computeKnownBits in some cases) by hoisting the common check for MinBitWidth >= OrigBitWidth above the extra check for lshr:

unsigned MinBitWidth = KnownRHS.getMaxValue()
                           .uadd_sat(APInt(SrcBitWidth, 1))
                           .getLimitedValue(SrcBitWidth);
if (MinBitWidth >= OrigBitWidth)
  return nullptr;
if (I->getOpcode() == Instruction::LShr) {
  KnownBits KnownLHS = computeKnownBits(I->getOperand(0), DL);
  if (KnownLHS.getMaxValue().getActiveBits() >= OrigBitWidth)
    return nullptr;
}
Itr.second.MinBitWidth = MinBitWidth;

llvm/test/Transforms/AggressiveInstCombine/trunc_shifts.ll

212

Similar to the previous shl example - this is another simplification to 0 that isn't handled by -instsimplify (but regular -instcombine gets it).

[anton-afanasyev]

In D108201#2952032, @spatel wrote:

In D108201#2951907, @anton-afanasyev wrote:

Rebase after shl bugfix

Add tests similar to 0988488ed461 (multiple widths) and 803270c0c691 (64-bit) for lshr patterns?

Sure, added tests

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

293

Thanks, used getActiveBits()

295–296

Thanks, duplicated check for efficiency.

llvm/test/Transforms/AggressiveInstCombine/trunc_shifts.ll

212

Ok, but here it is simple negative test, checking we do not fold to poisonous lshr i16 x, 16.

[anton-afanasyev]

Address comments

[spatel]

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

302–303

We already returned if MinBitWdith based on KnownRHS was too big, so this std::max is redundant?

llvm/test/Transforms/AggressiveInstCombine/trunc_shifts.ll

212

Yes, not a problem - just pointing out that there's another opportunity to improve InstSimplify and run some kind of cleanup in this pass.

[anton-afanasyev]

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

302–303

No, it isn't: we still use this updated MinBitWidth by setting it to instruction Info:

Itr.second.MinBitWidth = MinBitWidth;

This value is then used while computing common MinBitWidth in getMinBitWidth() function.

[spatel]

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

302–303

Ah, ok. Do we have a test to exercise that path? I didn't see any test failures when I made the change locally.

[anton-afanasyev]

Add test to exercise uncovered path

[anton-afanasyev]

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

302–303

Ok, added test to cover that path. With your change we get incorrect transformation: https://alive2.llvm.org/ce/z/fZ6jFb

[spatel]

LGTM

[akhuang]

looks like this caused a crash in some chromium code

c++ repro,

$ cat t.cpp
struct a {
  typedef unsigned char b;
};
struct c {
  static unsigned char *d(unsigned char *g, unsigned *p, int q) {
    *p = *g;
    if (*p)
      *p = q;
    return g;
  }
};
template <typename h> void i(int *, int, int, unsigned *, typename h::b *) {
  char *e = 0;
  unsigned char j;
  unsigned f;
  c::d(&j, &f, 33);
  *e = f >> 2;
}
int k, l, m;
unsigned n;
void o() { i<a>(&k, l, m, &n, (unsigned char *)o); }

$ clang -cc1 -fno-delete-null-pointer-checks -O3 -fsanitize=fuzzer-no-link -emit-llvm t.cpp

Also made an IR repro,

$ cat repro.ll
; ModuleID = 't.cpp'
source_filename = "t.cpp"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

$_Z1iI1aEvPiiiPjPNT_1bE = comdat any

; Function Attrs: mustprogress nounwind null_pointer_is_valid optforfuzzing
define linkonce_odr void @_Z1iI1aEvPiiiPjPNT_1bE(i32* %0, i32 %1, i32 %2, i32* %3, i8* %4) local_unnamed_addr #0 comdat {
_ZN1c1dEPhPji.exit:
  %shr = lshr i32 33, 2
  %conv = trunc i32 %shr to i8
  store i8 %conv, i8* null, align 536870912, !tbaa !6
  ret void
}

attributes #0 = { mustprogress nounwind null_pointer_is_valid optforfuzzing "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 14.0.0"}
!2 = !{!3, !3, i64 0}
!3 = !{!"int", !4, i64 0}
!4 = !{!"omnipotent char", !5, i64 0}
!5 = !{!"Simple C++ TBAA"}
!6 = !{!4, !4, i64 0}

$ opt -aggressive-instcombine -S repro.ll

[anton-afanasyev]

In D108201#2956220, @akhuang wrote:

looks like this caused a crash in some chromium code

Hi @akhuang , I'm not able to reproduce this crash. Could you please decribe your environment/crash output/stack trace?

> opt -aggressive-instcombine -S repro.ll 
; ModuleID = 'repro.ll'
source_filename = "repro.cpp"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

@k = local_unnamed_addr global i32 0, align 4
@l = local_unnamed_addr global i32 0, align 4
@m = local_unnamed_addr global i32 0, align 4
@n = local_unnamed_addr global i32 0, align 4

; Function Attrs: mustprogress nofree norecurse nosync nounwind null_pointer_is_valid optforfuzzing willreturn
define dso_local void @_Z1ov() local_unnamed_addr #0 {
entry:
  store i8 8, i8* null, align 536870912, !tbaa !2
  ret void
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind null_pointer_is_valid optforfuzzing willreturn "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 14.0.0 ([e-mail]:llvm/llvm-project.git b3a45e286fdfa73dd758472363dfafe7543cc077)"}
!2 = !{!3, !3, i64 0}
!3 = !{!"omnipotent char", !4, i64 0}
!4 = !{!"Simple C++ TBAA"}

> clang -cc1 -fno-delete-null-pointer-checks -O3 -fsanitize=fuzzer-no-link -emit-llvm  t.cpp
> cat t.ll
(the same output)

[spatel]

In D108201#2956690, @anton-afanasyev wrote:

In D108201#2956220, @akhuang wrote:

looks like this caused a crash in some chromium code

Hi @akhuang , I'm not able to reproduce this crash. Could you please decribe your environment/crash output/stack trace?

This should repro in a debug build, but might not be visible in release+asserts; I see it when building with clang on macOS, but it doesn't seem to repro on godbolt.
I think it's a simple bug and fixed with:
dd19f342fa21

[anton-afanasyev]

This should repro in a debug build, but might not be visible in release+asserts; I see it when building with clang on macOS, but it doesn't seem to repro on godbolt.
I think it's a simple bug and fixed with:
dd19f342fa21

Thank you!

[spatel]

In D108201#2957620, @anton-afanasyev wrote:

This should repro in a debug build, but might not be visible in release+asserts; I see it when building with clang on macOS, but it doesn't seem to repro on godbolt.
I think it's a simple bug and fixed with:
dd19f342fa21

Thank you!

Easy fix, but it does point to a larger problem (for the 3rd time in this patch set...) - we're seeing unsimplified IR, but this pass is not really prepared to handle that.
Maybe we'll sort this out when we try to make this pass run at -O2 instead of only -O3 (by having it run directly after -instcombine for example).

[spatel]

For reference, the exact bug was also responsible for:
https://llvm.org/PR51553
(and again, I can't remember why we run AIC before regular IC in the -O3 pipeline...)

[fhahn]

Not sure if it has been raised elsewhere already, but it looks like this is causing a regression: https://github.com/llvm/llvm-project/issues/51922

[anton-afanasyev]

In D108201#3249134, @fhahn wrote:

Not sure if it has been raised elsewhere already, but it looks like this is causing a regression: https://github.com/llvm/llvm-project/issues/51922

@fhahn Thanks for pointing this out! Looks like I've missed this during bugzilla migration.

llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

case Instruction::SExt:
     break;
   case Instruction::Add:
   case Instruction::Sub:
   case Instruction::Mul:
   case Instruction::And:
   case Instruction::Or:
   case Instruction::Xor:
   case Instruction::Shl:
+  case Instruction::LShr:
     Ops.push_back(I->getOperand(0));
     Ops.push_back(I->getOperand(1));
     break;
   case Instruction::Select:
     Ops.push_back(I->getOperand(1));
     Ops.push_back(I->getOperand(2));
     break;
   default:
case Instruction::SExt:
       break;
     case Instruction::Add:
     case Instruction::Sub:
     case Instruction::Mul:
     case Instruction::And:
     case Instruction::Or:
     case Instruction::Xor:
     case Instruction::Shl:
+    case Instruction::LShr:
     case Instruction::Select: {
       SmallVector<Value *, 2> Operands;
       getRelevantOperands(I, Operands);
       append_range(Worklist, Operands);
       break;
     }
     default:
       // TODO: Can handle more cases here:
       // 1. shufflevector, extractelement, insertelement
       // 2. udiv, urem
-      // 3. lshr, ashr
+      // 3. ashr
       // 4. phi node(and loop handling)
       // ...
       return false;
     }
   }
   return true;
 }
 
for (auto *U : I->users())
             return nullptr;
           DesiredBitWidth = ExtInstBitWidth;
         }
   }
 
   unsigned OrigBitWidth =
       CurrentTruncInst->getOperand(0)->getType()->getScalarSizeInBits();
 
-  // Initialize MinBitWidth for `shl` instructions with the minimum number
-  // that is greater than shift amount (i.e. shift amount + 1).
+  // Initialize MinBitWidth for shift instructions with the minimum number
+  // that is greater than shift amount (i.e. shift amount + 1). For `lshr`
+  // adjust MinBitWidth so that all potentially truncated bits of
+  // the value-to-be-shifted are zeros.
   // Also normalize MinBitWidth not to be greater than source bitwidth.
   for (auto &Itr : InstInfoMap) {
     Instruction *I = Itr.first;
-    if (I->getOpcode() == Instruction::Shl) {
+    if (I->getOpcode() == Instruction::Shl ||
+        I->getOpcode() == Instruction::LShr) {
       KnownBits KnownRHS = computeKnownBits(I->getOperand(1), DL);
       const unsigned SrcBitWidth = KnownRHS.getBitWidth();
       unsigned MinBitWidth = KnownRHS.getMaxValue()
                                  .uadd_sat(APInt(SrcBitWidth, 1))
                                  .getLimitedValue(SrcBitWidth);
+      if (I->getOpcode() == Instruction::LShr) {
+        KnownBits KnownLHS = computeKnownBits(I->getOperand(0), DL);
+        MinBitWidth = std::max(MinBitWidth,
+                               SrcBitWidth - KnownLHS.countMinLeadingZeros());
+      }
       if (MinBitWidth >= OrigBitWidth)
         return nullptr;
       Itr.second.MinBitWidth = MinBitWidth;
     }
   }
 
   // Calculate minimum allowed bit-width allowed for shrinking the currently
   // visited truncate's operand.
   unsigned MinBitWidth = getMinBitWidth();
 
   // Check that we can shrink to smaller bit-width than original one and that
   // it is similar to the DesiredBitWidth is such exists.
   if (MinBitWidth >= OrigBitWidth ||
       (DesiredBitWidth && DesiredBitWidth != MinBitWidth))
case Instruction::SExt: {
       break;
     }
     case Instruction::Add:
     case Instruction::Sub:
     case Instruction::Mul:
     case Instruction::And:
     case Instruction::Or:
     case Instruction::Xor:
-    case Instruction::Shl: {
+    case Instruction::Shl:
+    case Instruction::LShr: {
       Value *LHS = getReducedOperand(I->getOperand(0), SclTy);
       Value *RHS = getReducedOperand(I->getOperand(1), SclTy);
       Res = Builder.CreateBinOp((Instruction::BinaryOps)Opc, LHS, RHS);
+      // Preserve `exact` flag since truncation doesn't change exactness
+      if (Opc == Instruction::LShr)
+        cast<Instruction>(Res)->setIsExact(I->isExact());
       break;
     }
     case Instruction::Select: {
       Value *Op0 = I->getOperand(0);
       Value *LHS = getReducedOperand(I->getOperand(1), SclTy);
       Value *RHS = getReducedOperand(I->getOperand(2), SclTy);
       Res = Builder.CreateSelect(Op0, LHS, RHS);
       break;

llvm/test/Transforms/AggressiveInstCombine/pr50555.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -aggressive-instcombine -S | FileCheck %s
 
 define void @trunc_one_add(i16* %a, i8 %b) {
 ; CHECK-LABEL: @trunc_one_add(
-; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[B:%.*]] to i32
-; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 [[ZEXT]], 1
-; CHECK-NEXT:    [[ADD:%.*]] = add nsw i32 [[ZEXT]], [[SHR]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ADD]] to i16
-; CHECK-NEXT:    store i16 [[TRUNC]], i16* [[A:%.*]], align 2
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[B:%.*]] to i16
+; CHECK-NEXT:    [[SHR:%.*]] = lshr i16 [[ZEXT]], 1
+; CHECK-NEXT:    [[ADD:%.*]] = add i16 [[ZEXT]], [[SHR]]
+; CHECK-NEXT:    store i16 [[ADD]], i16* [[A:%.*]], align 2
 ; CHECK-NEXT:    ret void
 ;
   %zext = zext i8 %b to i32
   %shr = lshr i32 %zext, 1
   %add = add nsw i32 %zext, %shr
   %trunc = trunc i32 %add to i16
   store i16 %trunc, i16* %a, align 2
   ret void
 }
 
 define void @trunc_two_adds(i16* %a, i8 %b, i8 %c) {
 ; CHECK-LABEL: @trunc_two_adds(
-; CHECK-NEXT:    [[ZEXT1:%.*]] = zext i8 [[B:%.*]] to i32
-; CHECK-NEXT:    [[ZEXT2:%.*]] = zext i8 [[C:%.*]] to i32
-; CHECK-NEXT:    [[ADD1:%.*]] = add nuw nsw i32 [[ZEXT1]], [[ZEXT2]]
-; CHECK-NEXT:    [[SHR1:%.*]] = lshr i32 [[ADD1]], 1
-; CHECK-NEXT:    [[ADD2:%.*]] = add nuw nsw i32 [[ADD1]], [[SHR1]]
-; CHECK-NEXT:    [[SHR2:%.*]] = lshr i32 [[ADD2]], 2
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[SHR2]] to i16
-; CHECK-NEXT:    store i16 [[TRUNC]], i16* [[A:%.*]], align 2
+; CHECK-NEXT:    [[ZEXT1:%.*]] = zext i8 [[B:%.*]] to i16
+; CHECK-NEXT:    [[ZEXT2:%.*]] = zext i8 [[C:%.*]] to i16
+; CHECK-NEXT:    [[ADD1:%.*]] = add i16 [[ZEXT1]], [[ZEXT2]]
+; CHECK-NEXT:    [[SHR1:%.*]] = lshr i16 [[ADD1]], 1
+; CHECK-NEXT:    [[ADD2:%.*]] = add i16 [[ADD1]], [[SHR1]]
+; CHECK-NEXT:    [[SHR2:%.*]] = lshr i16 [[ADD2]], 2
+; CHECK-NEXT:    store i16 [[SHR2]], i16* [[A:%.*]], align 2
 ; CHECK-NEXT:    ret void
 ;
   %zext1 = zext i8 %b to i32
   %zext2 = zext i8 %c to i32
   %add1 = add nuw nsw i32 %zext1, %zext2
   %shr1 = lshr i32 %add1, 1
   %add2 = add nuw nsw i32 %add1, %shr1
   %shr2 = lshr i32 %add2, 2
   %trunc = trunc i32 %shr2 to i16
   store i16 %trunc, i16* %a, align 2
   ret void
 }

llvm/test/Transforms/AggressiveInstCombine/trunc_shifts.ll

;
   %z = zext i8 %x to i32
   %s = shl nsw i32 %z, 15
   %t = trunc i32 %s to i16
   ret i16 %t
 }
 
 define i16 @lshr_15(i16 %x) {
 ; CHECK-LABEL: @lshr_15(
-; CHECK-NEXT:    [[ZEXT:%.*]] = zext i16 [[X:%.*]] to i32
-; CHECK-NEXT:    [[LSHR:%.*]] = lshr i32 [[ZEXT]], 15
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[LSHR]] to i16
-; CHECK-NEXT:    ret i16 [[TRUNC]]
+; CHECK-NEXT:    [[LSHR:%.*]] = lshr i16 [[X:%.*]], 15
+; CHECK-NEXT:    ret i16 [[LSHR]]
 ;
   %zext = zext i16 %x to i32
   %lshr = lshr i32 %zext, 15
   %trunc = trunc i32 %lshr to i16
   ret i16 %trunc
 }
 
 ; Negative test
 
 define i16 @lshr_16(i16 %x) {
 ; CHECK-LABEL: @lshr_16(
 ; CHECK-NEXT:    [[ZEXT:%.*]] = zext i16 [[X:%.*]] to i32
 ; CHECK-NEXT:    [[LSHR:%.*]] = lshr i32 [[ZEXT]], 16
 ; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[LSHR]] to i16
 ; CHECK-NEXT:    ret i16 [[TRUNC]]
 ;
   %zext = zext i16 %x to i32
   %lshr = lshr i32 %zext, 16
   %trunc = trunc i32 %lshr to i16
   ret i16 %trunc
 }
 
 ; Negative test
 
 define i16 @lshr_var_shift_amount(i8 %x, i8 %amt) {
 ; CHECK-LABEL: @lshr_var_shift_amount(
;
   %a = add i32 %s, %z
   %s2 = lshr i32 %a, 2
   %t = trunc i32 %s2 to i16
   ret i16 %t
 }
 
 define i16 @lshr_var_bounded_shift_amount(i8 %x, i8 %amt) {
 ; CHECK-LABEL: @lshr_var_bounded_shift_amount(
-; CHECK-NEXT:    [[Z:%.*]] = zext i8 [[X:%.*]] to i32
-; CHECK-NEXT:    [[ZA:%.*]] = zext i8 [[AMT:%.*]] to i32
-; CHECK-NEXT:    [[ZA2:%.*]] = and i32 [[ZA]], 15
-; CHECK-NEXT:    [[S:%.*]] = lshr i32 [[Z]], [[ZA2]]
-; CHECK-NEXT:    [[A:%.*]] = add i32 [[S]], [[Z]]
-; CHECK-NEXT:    [[S2:%.*]] = lshr i32 [[A]], 2
-; CHECK-NEXT:    [[T:%.*]] = trunc i32 [[S2]] to i16
-; CHECK-NEXT:    ret i16 [[T]]
+; CHECK-NEXT:    [[Z:%.*]] = zext i8 [[X:%.*]] to i16
+; CHECK-NEXT:    [[ZA:%.*]] = zext i8 [[AMT:%.*]] to i16
+; CHECK-NEXT:    [[ZA2:%.*]] = and i16 [[ZA]], 15
+; CHECK-NEXT:    [[S:%.*]] = lshr i16 [[Z]], [[ZA2]]
+; CHECK-NEXT:    [[A:%.*]] = add i16 [[S]], [[Z]]
+; CHECK-NEXT:    [[S2:%.*]] = lshr i16 [[A]], 2
+; CHECK-NEXT:    ret i16 [[S2]]
 ;
   %z = zext i8 %x to i32
   %za = zext i8 %amt to i32
   %za2 = and i32 %za, 15
   %s = lshr i32 %z, %za2
   %a = add i32 %s, %z
   %s2 = lshr i32 %a, 2
   %t = trunc i32 %s2 to i16
   ret i16 %t
 }
 
 define void @lshr_big_dag(i16* %a, i8 %b, i8 %c) {
 ; CHECK-LABEL: @lshr_big_dag(
-; CHECK-NEXT:    [[ZEXT1:%.*]] = zext i8 [[B:%.*]] to i32
-; CHECK-NEXT:    [[ZEXT2:%.*]] = zext i8 [[C:%.*]] to i32
-; CHECK-NEXT:    [[ADD1:%.*]] = add i32 [[ZEXT1]], [[ZEXT2]]
-; CHECK-NEXT:    [[SFT1:%.*]] = and i32 [[ADD1]], 15
-; CHECK-NEXT:    [[SHR1:%.*]] = lshr i32 [[ADD1]], [[SFT1]]
-; CHECK-NEXT:    [[ADD2:%.*]] = add i32 [[ADD1]], [[SHR1]]
-; CHECK-NEXT:    [[SFT2:%.*]] = and i32 [[ADD2]], 7
-; CHECK-NEXT:    [[SHR2:%.*]] = lshr i32 [[ADD2]], [[SFT2]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[SHR2]] to i16
-; CHECK-NEXT:    store i16 [[TRUNC]], i16* [[A:%.*]], align 2
+; CHECK-NEXT:    [[ZEXT1:%.*]] = zext i8 [[B:%.*]] to i16
+; CHECK-NEXT:    [[ZEXT2:%.*]] = zext i8 [[C:%.*]] to i16
+; CHECK-NEXT:    [[ADD1:%.*]] = add i16 [[ZEXT1]], [[ZEXT2]]
+; CHECK-NEXT:    [[SFT1:%.*]] = and i16 [[ADD1]], 15
+; CHECK-NEXT:    [[SHR1:%.*]] = lshr i16 [[ADD1]], [[SFT1]]
+; CHECK-NEXT:    [[ADD2:%.*]] = add i16 [[ADD1]], [[SHR1]]
+; CHECK-NEXT:    [[SFT2:%.*]] = and i16 [[ADD2]], 7
+; CHECK-NEXT:    [[SHR2:%.*]] = lshr i16 [[ADD2]], [[SFT2]]
+; CHECK-NEXT:    store i16 [[SHR2]], i16* [[A:%.*]], align 2
 ; CHECK-NEXT:    ret void
 ;
   %zext1 = zext i8 %b to i32
   %zext2 = zext i8 %c to i32
   %add1 = add i32 %zext1, %zext2
   %sft1 = and i32 %add1, 15
   %shr1 = lshr i32 %add1, %sft1
   %add2 = add i32 %add1, %shr1
   %sft2 = and i32 %add2, 7
   %shr2 = lshr i32 %add2, %sft2
   %trunc = trunc i32 %shr2 to i16
   store i16 %trunc, i16* %a, align 2
   ret void
 }
 
 define <2 x i16> @lshr_vector(<2 x i8> %x) {
 ; CHECK-LABEL: @lshr_vector(
-; CHECK-NEXT:    [[Z:%.*]] = zext <2 x i8> [[X:%.*]] to <2 x i32>
-; CHECK-NEXT:    [[ZA:%.*]] = and <2 x i32> [[Z]], <i32 7, i32 8>
-; CHECK-NEXT:    [[S:%.*]] = lshr <2 x i32> [[Z]], [[ZA]]
-; CHECK-NEXT:    [[A:%.*]] = add <2 x i32> [[S]], [[Z]]
-; CHECK-NEXT:    [[S2:%.*]] = lshr <2 x i32> [[A]], <i32 4, i32 5>
-; CHECK-NEXT:    [[T:%.*]] = trunc <2 x i32> [[S2]] to <2 x i16>
-; CHECK-NEXT:    ret <2 x i16> [[T]]
+; CHECK-NEXT:    [[Z:%.*]] = zext <2 x i8> [[X:%.*]] to <2 x i16>
+; CHECK-NEXT:    [[ZA:%.*]] = and <2 x i16> [[Z]], <i16 7, i16 8>
+; CHECK-NEXT:    [[S:%.*]] = lshr <2 x i16> [[Z]], [[ZA]]
+; CHECK-NEXT:    [[A:%.*]] = add <2 x i16> [[S]], [[Z]]
+; CHECK-NEXT:    [[S2:%.*]] = lshr <2 x i16> [[A]], <i16 4, i16 5>
+; CHECK-NEXT:    ret <2 x i16> [[S2]]
 ;
   %z = zext <2 x i8> %x to <2 x i32>
   %za = and <2 x i32> %z, <i32 7, i32 8>
   %s = lshr <2 x i32> %z, %za
   %a = add <2 x i32> %s, %z
   %s2 = lshr <2 x i32> %a, <i32 4, i32 5>
   %t = trunc <2 x i32> %s2 to <2 x i16>
   ret <2 x i16> %t
;
   %a = add <2 x i32> %s, %z
   %s2 = lshr <2 x i32> %a, <i32 16, i32 5>
   %t = trunc <2 x i32> %s2 to <2 x i16>
   ret <2 x i16> %t
 }
 
 define i16 @lshr_exact(i16 %x) {
 ; CHECK-LABEL: @lshr_exact(
-; CHECK-NEXT:    [[ZEXT:%.*]] = zext i16 [[X:%.*]] to i32
-; CHECK-NEXT:    [[LSHR:%.*]] = lshr exact i32 [[ZEXT]], 15
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[LSHR]] to i16
-; CHECK-NEXT:    ret i16 [[TRUNC]]
+; CHECK-NEXT:    [[LSHR:%.*]] = lshr exact i16 [[X:%.*]], 15
+; CHECK-NEXT:    ret i16 [[LSHR]]
 ;
   %zext = zext i16 %x to i32
   %lshr = lshr exact i32 %zext, 15
   %trunc = trunc i32 %lshr to i16
   ret i16 %trunc
 }
 
 ; Negative test

llvm/test/Transforms/PhaseOrdering/X86/pr50555.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -O3 -S -mtriple=x86_64-- | FileCheck %s --check-prefixes=SSE
 ; RUN: opt < %s -O3 -S -mtriple=x86_64-- -mattr=avx | FileCheck %s --check-prefixes=AVX
 
 define void @trunc_through_one_add(i16* noalias %0, i8* noalias readonly %1) {
 ; SSE-LABEL: @trunc_through_one_add(
-; SSE-NEXT:    [[TMP3:%.*]] = bitcast i8* [[TMP1:%.*]] to <4 x i8>*
-; SSE-NEXT:    [[TMP4:%.*]] = load <4 x i8>, <4 x i8>* [[TMP3]], align 1
-; SSE-NEXT:    [[TMP5:%.*]] = zext <4 x i8> [[TMP4]] to <4 x i32>
-; SSE-NEXT:    [[TMP6:%.*]] = lshr <4 x i32> [[TMP5]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP7:%.*]] = add nuw nsw <4 x i32> [[TMP6]], [[TMP5]]
-; SSE-NEXT:    [[TMP8:%.*]] = lshr <4 x i32> [[TMP7]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP9:%.*]] = trunc <4 x i32> [[TMP8]] to <4 x i16>
-; SSE-NEXT:    [[TMP10:%.*]] = bitcast i16* [[TMP0:%.*]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP9]], <4 x i16>* [[TMP10]], align 2
-; SSE-NEXT:    [[TMP11:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 4
-; SSE-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 4
-; SSE-NEXT:    [[TMP13:%.*]] = bitcast i8* [[TMP11]] to <4 x i8>*
-; SSE-NEXT:    [[TMP14:%.*]] = load <4 x i8>, <4 x i8>* [[TMP13]], align 1
-; SSE-NEXT:    [[TMP15:%.*]] = zext <4 x i8> [[TMP14]] to <4 x i32>
-; SSE-NEXT:    [[TMP16:%.*]] = lshr <4 x i32> [[TMP15]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP17:%.*]] = add nuw nsw <4 x i32> [[TMP16]], [[TMP15]]
-; SSE-NEXT:    [[TMP18:%.*]] = lshr <4 x i32> [[TMP17]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP19:%.*]] = trunc <4 x i32> [[TMP18]] to <4 x i16>
-; SSE-NEXT:    [[TMP20:%.*]] = bitcast i16* [[TMP12]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP19]], <4 x i16>* [[TMP20]], align 2
-; SSE-NEXT:    [[TMP21:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 8
-; SSE-NEXT:    [[TMP22:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 8
-; SSE-NEXT:    [[TMP23:%.*]] = bitcast i8* [[TMP21]] to <4 x i8>*
-; SSE-NEXT:    [[TMP24:%.*]] = load <4 x i8>, <4 x i8>* [[TMP23]], align 1
-; SSE-NEXT:    [[TMP25:%.*]] = zext <4 x i8> [[TMP24]] to <4 x i32>
-; SSE-NEXT:    [[TMP26:%.*]] = lshr <4 x i32> [[TMP25]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP27:%.*]] = add nuw nsw <4 x i32> [[TMP26]], [[TMP25]]
-; SSE-NEXT:    [[TMP28:%.*]] = lshr <4 x i32> [[TMP27]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP29:%.*]] = trunc <4 x i32> [[TMP28]] to <4 x i16>
-; SSE-NEXT:    [[TMP30:%.*]] = bitcast i16* [[TMP22]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP29]], <4 x i16>* [[TMP30]], align 2
-; SSE-NEXT:    [[TMP31:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 12
-; SSE-NEXT:    [[TMP32:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 12
-; SSE-NEXT:    [[TMP33:%.*]] = bitcast i8* [[TMP31]] to <4 x i8>*
-; SSE-NEXT:    [[TMP34:%.*]] = load <4 x i8>, <4 x i8>* [[TMP33]], align 1
-; SSE-NEXT:    [[TMP35:%.*]] = zext <4 x i8> [[TMP34]] to <4 x i32>
-; SSE-NEXT:    [[TMP36:%.*]] = lshr <4 x i32> [[TMP35]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP37:%.*]] = add nuw nsw <4 x i32> [[TMP36]], [[TMP35]]
-; SSE-NEXT:    [[TMP38:%.*]] = lshr <4 x i32> [[TMP37]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP39:%.*]] = trunc <4 x i32> [[TMP38]] to <4 x i16>
-; SSE-NEXT:    [[TMP40:%.*]] = bitcast i16* [[TMP32]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP39]], <4 x i16>* [[TMP40]], align 2
+; SSE-NEXT:    [[TMP3:%.*]] = bitcast i8* [[TMP1:%.*]] to <8 x i8>*
+; SSE-NEXT:    [[TMP4:%.*]] = load <8 x i8>, <8 x i8>* [[TMP3]], align 1
+; SSE-NEXT:    [[TMP5:%.*]] = zext <8 x i8> [[TMP4]] to <8 x i16>
+; SSE-NEXT:    [[TMP6:%.*]] = lshr <8 x i16> [[TMP5]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
+; SSE-NEXT:    [[TMP7:%.*]] = add nuw nsw <8 x i16> [[TMP6]], [[TMP5]]
+; SSE-NEXT:    [[TMP8:%.*]] = lshr <8 x i16> [[TMP7]], <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
+; SSE-NEXT:    [[TMP9:%.*]] = bitcast i16* [[TMP0:%.*]] to <8 x i16>*
+; SSE-NEXT:    store <8 x i16> [[TMP8]], <8 x i16>* [[TMP9]], align 2
+; SSE-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 8
+; SSE-NEXT:    [[TMP11:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 8
+; SSE-NEXT:    [[TMP12:%.*]] = bitcast i8* [[TMP10]] to <8 x i8>*
+; SSE-NEXT:    [[TMP13:%.*]] = load <8 x i8>, <8 x i8>* [[TMP12]], align 1
+; SSE-NEXT:    [[TMP14:%.*]] = zext <8 x i8> [[TMP13]] to <8 x i16>
+; SSE-NEXT:    [[TMP15:%.*]] = lshr <8 x i16> [[TMP14]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
+; SSE-NEXT:    [[TMP16:%.*]] = add nuw nsw <8 x i16> [[TMP15]], [[TMP14]]
+; SSE-NEXT:    [[TMP17:%.*]] = lshr <8 x i16> [[TMP16]], <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
+; SSE-NEXT:    [[TMP18:%.*]] = bitcast i16* [[TMP11]] to <8 x i16>*
+; SSE-NEXT:    store <8 x i16> [[TMP17]], <8 x i16>* [[TMP18]], align 2
 ; SSE-NEXT:    ret void
 ;
 ; AVX-LABEL: @trunc_through_one_add(
-; AVX-NEXT:    [[TMP3:%.*]] = bitcast i8* [[TMP1:%.*]] to <8 x i8>*
-; AVX-NEXT:    [[TMP4:%.*]] = load <8 x i8>, <8 x i8>* [[TMP3]], align 1
-; AVX-NEXT:    [[TMP5:%.*]] = zext <8 x i8> [[TMP4]] to <8 x i32>
-; AVX-NEXT:    [[TMP6:%.*]] = lshr <8 x i32> [[TMP5]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
-; AVX-NEXT:    [[TMP7:%.*]] = add nuw nsw <8 x i32> [[TMP6]], [[TMP5]]
-; AVX-NEXT:    [[TMP8:%.*]] = lshr <8 x i32> [[TMP7]], <i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2>
-; AVX-NEXT:    [[TMP9:%.*]] = trunc <8 x i32> [[TMP8]] to <8 x i16>
-; AVX-NEXT:    [[TMP10:%.*]] = bitcast i16* [[TMP0:%.*]] to <8 x i16>*
-; AVX-NEXT:    store <8 x i16> [[TMP9]], <8 x i16>* [[TMP10]], align 2
-; AVX-NEXT:    [[TMP11:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 8
-; AVX-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 8
-; AVX-NEXT:    [[TMP13:%.*]] = bitcast i8* [[TMP11]] to <8 x i8>*
-; AVX-NEXT:    [[TMP14:%.*]] = load <8 x i8>, <8 x i8>* [[TMP13]], align 1
-; AVX-NEXT:    [[TMP15:%.*]] = zext <8 x i8> [[TMP14]] to <8 x i32>
-; AVX-NEXT:    [[TMP16:%.*]] = lshr <8 x i32> [[TMP15]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
-; AVX-NEXT:    [[TMP17:%.*]] = add nuw nsw <8 x i32> [[TMP16]], [[TMP15]]
-; AVX-NEXT:    [[TMP18:%.*]] = lshr <8 x i32> [[TMP17]], <i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2>
-; AVX-NEXT:    [[TMP19:%.*]] = trunc <8 x i32> [[TMP18]] to <8 x i16>
-; AVX-NEXT:    [[TMP20:%.*]] = bitcast i16* [[TMP12]] to <8 x i16>*
-; AVX-NEXT:    store <8 x i16> [[TMP19]], <8 x i16>* [[TMP20]], align 2
+; AVX-NEXT:    [[TMP3:%.*]] = bitcast i8* [[TMP1:%.*]] to <16 x i8>*
+; AVX-NEXT:    [[TMP4:%.*]] = load <16 x i8>, <16 x i8>* [[TMP3]], align 1
+; AVX-NEXT:    [[TMP5:%.*]] = zext <16 x i8> [[TMP4]] to <16 x i16>
+; AVX-NEXT:    [[TMP6:%.*]] = lshr <16 x i16> [[TMP5]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
+; AVX-NEXT:    [[TMP7:%.*]] = add nuw nsw <16 x i16> [[TMP6]], [[TMP5]]
+; AVX-NEXT:    [[TMP8:%.*]] = lshr <16 x i16> [[TMP7]], <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
+; AVX-NEXT:    [[TMP9:%.*]] = bitcast i16* [[TMP0:%.*]] to <16 x i16>*
+; AVX-NEXT:    store <16 x i16> [[TMP8]], <16 x i16>* [[TMP9]], align 2
 ; AVX-NEXT:    ret void
 ;
   %3 = load i8, i8* %1, align 1
   %4 = zext i8 %3 to i32
   %5 = lshr i32 %4, 1
   %6 = add nuw nsw i32 %5, %4
   %7 = lshr i32 %6, 2
   %8 = trunc i32 %7 to i16
;
   %127 = trunc i32 %126 to i16
   %128 = getelementptr inbounds i16, i16* %0, i64 15
   store i16 %127, i16* %128, align 2
   ret void
 }
 
 define void @trunc_through_two_adds(i16* noalias %0, i8* noalias readonly %1, i8* noalias readonly %2) {
 ; SSE-LABEL: @trunc_through_two_adds(
-; SSE-NEXT:    [[TMP4:%.*]] = bitcast i8* [[TMP1:%.*]] to <4 x i8>*
-; SSE-NEXT:    [[TMP5:%.*]] = load <4 x i8>, <4 x i8>* [[TMP4]], align 1
-; SSE-NEXT:    [[TMP6:%.*]] = zext <4 x i8> [[TMP5]] to <4 x i32>
-; SSE-NEXT:    [[TMP7:%.*]] = bitcast i8* [[TMP2:%.*]] to <4 x i8>*
-; SSE-NEXT:    [[TMP8:%.*]] = load <4 x i8>, <4 x i8>* [[TMP7]], align 1
-; SSE-NEXT:    [[TMP9:%.*]] = zext <4 x i8> [[TMP8]] to <4 x i32>
-; SSE-NEXT:    [[TMP10:%.*]] = add nuw nsw <4 x i32> [[TMP9]], [[TMP6]]
-; SSE-NEXT:    [[TMP11:%.*]] = lshr <4 x i32> [[TMP10]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP12:%.*]] = add nuw nsw <4 x i32> [[TMP11]], [[TMP10]]
-; SSE-NEXT:    [[TMP13:%.*]] = lshr <4 x i32> [[TMP12]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP14:%.*]] = trunc <4 x i32> [[TMP13]] to <4 x i16>
-; SSE-NEXT:    [[TMP15:%.*]] = bitcast i16* [[TMP0:%.*]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP14]], <4 x i16>* [[TMP15]], align 2
-; SSE-NEXT:    [[TMP16:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 4
-; SSE-NEXT:    [[TMP17:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i64 4
-; SSE-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 4
-; SSE-NEXT:    [[TMP19:%.*]] = bitcast i8* [[TMP16]] to <4 x i8>*
-; SSE-NEXT:    [[TMP20:%.*]] = load <4 x i8>, <4 x i8>* [[TMP19]], align 1
-; SSE-NEXT:    [[TMP21:%.*]] = zext <4 x i8> [[TMP20]] to <4 x i32>
-; SSE-NEXT:    [[TMP22:%.*]] = bitcast i8* [[TMP17]] to <4 x i8>*
-; SSE-NEXT:    [[TMP23:%.*]] = load <4 x i8>, <4 x i8>* [[TMP22]], align 1
-; SSE-NEXT:    [[TMP24:%.*]] = zext <4 x i8> [[TMP23]] to <4 x i32>
-; SSE-NEXT:    [[TMP25:%.*]] = add nuw nsw <4 x i32> [[TMP24]], [[TMP21]]
-; SSE-NEXT:    [[TMP26:%.*]] = lshr <4 x i32> [[TMP25]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP27:%.*]] = add nuw nsw <4 x i32> [[TMP26]], [[TMP25]]
-; SSE-NEXT:    [[TMP28:%.*]] = lshr <4 x i32> [[TMP27]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP29:%.*]] = trunc <4 x i32> [[TMP28]] to <4 x i16>
-; SSE-NEXT:    [[TMP30:%.*]] = bitcast i16* [[TMP18]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP29]], <4 x i16>* [[TMP30]], align 2
-; SSE-NEXT:    [[TMP31:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 8
-; SSE-NEXT:    [[TMP32:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i64 8
-; SSE-NEXT:    [[TMP33:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 8
-; SSE-NEXT:    [[TMP34:%.*]] = bitcast i8* [[TMP31]] to <4 x i8>*
-; SSE-NEXT:    [[TMP35:%.*]] = load <4 x i8>, <4 x i8>* [[TMP34]], align 1
-; SSE-NEXT:    [[TMP36:%.*]] = zext <4 x i8> [[TMP35]] to <4 x i32>
-; SSE-NEXT:    [[TMP37:%.*]] = bitcast i8* [[TMP32]] to <4 x i8>*
-; SSE-NEXT:    [[TMP38:%.*]] = load <4 x i8>, <4 x i8>* [[TMP37]], align 1
-; SSE-NEXT:    [[TMP39:%.*]] = zext <4 x i8> [[TMP38]] to <4 x i32>
-; SSE-NEXT:    [[TMP40:%.*]] = add nuw nsw <4 x i32> [[TMP39]], [[TMP36]]
-; SSE-NEXT:    [[TMP41:%.*]] = lshr <4 x i32> [[TMP40]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP42:%.*]] = add nuw nsw <4 x i32> [[TMP41]], [[TMP40]]
-; SSE-NEXT:    [[TMP43:%.*]] = lshr <4 x i32> [[TMP42]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP44:%.*]] = trunc <4 x i32> [[TMP43]] to <4 x i16>
-; SSE-NEXT:    [[TMP45:%.*]] = bitcast i16* [[TMP33]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP44]], <4 x i16>* [[TMP45]], align 2
-; SSE-NEXT:    [[TMP46:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 12
-; SSE-NEXT:    [[TMP47:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i64 12
-; SSE-NEXT:    [[TMP48:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 12
-; SSE-NEXT:    [[TMP49:%.*]] = bitcast i8* [[TMP46]] to <4 x i8>*
-; SSE-NEXT:    [[TMP50:%.*]] = load <4 x i8>, <4 x i8>* [[TMP49]], align 1
-; SSE-NEXT:    [[TMP51:%.*]] = zext <4 x i8> [[TMP50]] to <4 x i32>
-; SSE-NEXT:    [[TMP52:%.*]] = bitcast i8* [[TMP47]] to <4 x i8>*
-; SSE-NEXT:    [[TMP53:%.*]] = load <4 x i8>, <4 x i8>* [[TMP52]], align 1
-; SSE-NEXT:    [[TMP54:%.*]] = zext <4 x i8> [[TMP53]] to <4 x i32>
-; SSE-NEXT:    [[TMP55:%.*]] = add nuw nsw <4 x i32> [[TMP54]], [[TMP51]]
-; SSE-NEXT:    [[TMP56:%.*]] = lshr <4 x i32> [[TMP55]], <i32 1, i32 1, i32 1, i32 1>
-; SSE-NEXT:    [[TMP57:%.*]] = add nuw nsw <4 x i32> [[TMP56]], [[TMP55]]
-; SSE-NEXT:    [[TMP58:%.*]] = lshr <4 x i32> [[TMP57]], <i32 2, i32 2, i32 2, i32 2>
-; SSE-NEXT:    [[TMP59:%.*]] = trunc <4 x i32> [[TMP58]] to <4 x i16>
-; SSE-NEXT:    [[TMP60:%.*]] = bitcast i16* [[TMP48]] to <4 x i16>*
-; SSE-NEXT:    store <4 x i16> [[TMP59]], <4 x i16>* [[TMP60]], align 2
+; SSE-NEXT:    [[TMP4:%.*]] = bitcast i8* [[TMP1:%.*]] to <8 x i8>*
+; SSE-NEXT:    [[TMP5:%.*]] = load <8 x i8>, <8 x i8>* [[TMP4]], align 1
+; SSE-NEXT:    [[TMP6:%.*]] = zext <8 x i8> [[TMP5]] to <8 x i16>
+; SSE-NEXT:    [[TMP7:%.*]] = bitcast i8* [[TMP2:%.*]] to <8 x i8>*
+; SSE-NEXT:    [[TMP8:%.*]] = load <8 x i8>, <8 x i8>* [[TMP7]], align 1
+; SSE-NEXT:    [[TMP9:%.*]] = zext <8 x i8> [[TMP8]] to <8 x i16>
+; SSE-NEXT:    [[TMP10:%.*]] = add nuw nsw <8 x i16> [[TMP9]], [[TMP6]]
+; SSE-NEXT:    [[TMP11:%.*]] = lshr <8 x i16> [[TMP10]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
+; SSE-NEXT:    [[TMP12:%.*]] = add nuw nsw <8 x i16> [[TMP11]], [[TMP10]]
+; SSE-NEXT:    [[TMP13:%.*]] = lshr <8 x i16> [[TMP12]], <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
+; SSE-NEXT:    [[TMP14:%.*]] = bitcast i16* [[TMP0:%.*]] to <8 x i16>*
+; SSE-NEXT:    store <8 x i16> [[TMP13]], <8 x i16>* [[TMP14]], align 2
+; SSE-NEXT:    [[TMP15:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 8
+; SSE-NEXT:    [[TMP16:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i64 8
+; SSE-NEXT:    [[TMP17:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 8
+; SSE-NEXT:    [[TMP18:%.*]] = bitcast i8* [[TMP15]] to <8 x i8>*
+; SSE-NEXT:    [[TMP19:%.*]] = load <8 x i8>, <8 x i8>* [[TMP18]], align 1
+; SSE-NEXT:    [[TMP20:%.*]] = zext <8 x i8> [[TMP19]] to <8 x i16>
+; SSE-NEXT:    [[TMP21:%.*]] = bitcast i8* [[TMP16]] to <8 x i8>*
+; SSE-NEXT:    [[TMP22:%.*]] = load <8 x i8>, <8 x i8>* [[TMP21]], align 1
+; SSE-NEXT:    [[TMP23:%.*]] = zext <8 x i8> [[TMP22]] to <8 x i16>
+; SSE-NEXT:    [[TMP24:%.*]] = add nuw nsw <8 x i16> [[TMP23]], [[TMP20]]
+; SSE-NEXT:    [[TMP25:%.*]] = lshr <8 x i16> [[TMP24]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
+; SSE-NEXT:    [[TMP26:%.*]] = add nuw nsw <8 x i16> [[TMP25]], [[TMP24]]
+; SSE-NEXT:    [[TMP27:%.*]] = lshr <8 x i16> [[TMP26]], <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
+; SSE-NEXT:    [[TMP28:%.*]] = bitcast i16* [[TMP17]] to <8 x i16>*
+; SSE-NEXT:    store <8 x i16> [[TMP27]], <8 x i16>* [[TMP28]], align 2
 ; SSE-NEXT:    ret void
 ;
 ; AVX-LABEL: @trunc_through_two_adds(
-; AVX-NEXT:    [[TMP4:%.*]] = bitcast i8* [[TMP1:%.*]] to <8 x i8>*
-; AVX-NEXT:    [[TMP5:%.*]] = load <8 x i8>, <8 x i8>* [[TMP4]], align 1
-; AVX-NEXT:    [[TMP6:%.*]] = zext <8 x i8> [[TMP5]] to <8 x i32>
-; AVX-NEXT:    [[TMP7:%.*]] = bitcast i8* [[TMP2:%.*]] to <8 x i8>*
-; AVX-NEXT:    [[TMP8:%.*]] = load <8 x i8>, <8 x i8>* [[TMP7]], align 1
-; AVX-NEXT:    [[TMP9:%.*]] = zext <8 x i8> [[TMP8]] to <8 x i32>
-; AVX-NEXT:    [[TMP10:%.*]] = add nuw nsw <8 x i32> [[TMP9]], [[TMP6]]
-; AVX-NEXT:    [[TMP11:%.*]] = lshr <8 x i32> [[TMP10]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
-; AVX-NEXT:    [[TMP12:%.*]] = add nuw nsw <8 x i32> [[TMP11]], [[TMP10]]
-; AVX-NEXT:    [[TMP13:%.*]] = lshr <8 x i32> [[TMP12]], <i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2>
-; AVX-NEXT:    [[TMP14:%.*]] = trunc <8 x i32> [[TMP13]] to <8 x i16>
-; AVX-NEXT:    [[TMP15:%.*]] = bitcast i16* [[TMP0:%.*]] to <8 x i16>*
-; AVX-NEXT:    store <8 x i16> [[TMP14]], <8 x i16>* [[TMP15]], align 2
-; AVX-NEXT:    [[TMP16:%.*]] = getelementptr inbounds i8, i8* [[TMP1]], i64 8
-; AVX-NEXT:    [[TMP17:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i64 8
-; AVX-NEXT:    [[TMP18:%.*]] = getelementptr inbounds i16, i16* [[TMP0]], i64 8
-; AVX-NEXT:    [[TMP19:%.*]] = bitcast i8* [[TMP16]] to <8 x i8>*
-; AVX-NEXT:    [[TMP20:%.*]] = load <8 x i8>, <8 x i8>* [[TMP19]], align 1
-; AVX-NEXT:    [[TMP21:%.*]] = zext <8 x i8> [[TMP20]] to <8 x i32>
-; AVX-NEXT:    [[TMP22:%.*]] = bitcast i8* [[TMP17]] to <8 x i8>*
-; AVX-NEXT:    [[TMP23:%.*]] = load <8 x i8>, <8 x i8>* [[TMP22]], align 1
-; AVX-NEXT:    [[TMP24:%.*]] = zext <8 x i8> [[TMP23]] to <8 x i32>
-; AVX-NEXT:    [[TMP25:%.*]] = add nuw nsw <8 x i32> [[TMP24]], [[TMP21]]
-; AVX-NEXT:    [[TMP26:%.*]] = lshr <8 x i32> [[TMP25]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
-; AVX-NEXT:    [[TMP27:%.*]] = add nuw nsw <8 x i32> [[TMP26]], [[TMP25]]
-; AVX-NEXT:    [[TMP28:%.*]] = lshr <8 x i32> [[TMP27]], <i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2>
-; AVX-NEXT:    [[TMP29:%.*]] = trunc <8 x i32> [[TMP28]] to <8 x i16>
-; AVX-NEXT:    [[TMP30:%.*]] = bitcast i16* [[TMP18]] to <8 x i16>*
-; AVX-NEXT:    store <8 x i16> [[TMP29]], <8 x i16>* [[TMP30]], align 2
+; AVX-NEXT:    [[TMP4:%.*]] = bitcast i8* [[TMP1:%.*]] to <16 x i8>*
+; AVX-NEXT:    [[TMP5:%.*]] = load <16 x i8>, <16 x i8>* [[TMP4]], align 1
+; AVX-NEXT:    [[TMP6:%.*]] = zext <16 x i8> [[TMP5]] to <16 x i16>
+; AVX-NEXT:    [[TMP7:%.*]] = bitcast i8* [[TMP2:%.*]] to <16 x i8>*
+; AVX-NEXT:    [[TMP8:%.*]] = load <16 x i8>, <16 x i8>* [[TMP7]], align 1
+; AVX-NEXT:    [[TMP9:%.*]] = zext <16 x i8> [[TMP8]] to <16 x i16>
+; AVX-NEXT:    [[TMP10:%.*]] = add nuw nsw <16 x i16> [[TMP9]], [[TMP6]]
+; AVX-NEXT:    [[TMP11:%.*]] = lshr <16 x i16> [[TMP10]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
+; AVX-NEXT:    [[TMP12:%.*]] = add nuw nsw <16 x i16> [[TMP11]], [[TMP10]]
+; AVX-NEXT:    [[TMP13:%.*]] = lshr <16 x i16> [[TMP12]], <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
+; AVX-NEXT:    [[TMP14:%.*]] = bitcast i16* [[TMP0:%.*]] to <16 x i16>*
+; AVX-NEXT:    store <16 x i16> [[TMP13]], <16 x i16>* [[TMP14]], align 2
 ; AVX-NEXT:    ret void
 ;
   %4 = load i8, i8* %1, align 1
   %5 = zext i8 %4 to i32
   %6 = load i8, i8* %2, align 1
   %7 = zext i8 %6 to i32
   %8 = add nuw nsw i32 %7, %5
   %9 = lshr i32 %8, 1