[SCEV] Add nuw/nsw to mul ops in StrengthenNoWrapFlags where safe.

[jlebar]

Summary

Previously we would add them for adds, but not multiplies.

[jlebar]

Fix all remaining tests.

[sanjoy]

lgtm!

[jlebar]

Thank you for the reviews!

Here goes nothing...

llvm/trunk/lib/Analysis/ScalarEvolution.cpp

StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
   };
 
   if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
     Flags =
         ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
 
   SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
 
-  if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr &&
-      Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) {
+  if (SignOrUnsignWrap != SignOrUnsignMask &&
+      (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 &&
+      isa<SCEVConstant>(Ops[0])) {
 
-    // (A + C) --> (A + C)<nsw> if the addition does not sign overflow
-    // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow
+    auto Opcode = [&] {
+      switch (Type) {
+      case scAddExpr:
+        return Instruction::Add;
+      case scMulExpr:
+        return Instruction::Mul;
+      default:
+        llvm_unreachable("Unexpected SCEV op.");
+      }
+    }();
 
     const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
+
+    // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
     if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
       auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
-          Instruction::Add, C, OBO::NoSignedWrap);
+          Opcode, C, OBO::NoSignedWrap);
       if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
         Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
     }
+
+    // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
     if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
       auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
           Instruction::Add, C, OBO::NoUnsignedWrap);
       if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
         Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
     }
   }
 

llvm/trunk/test/Analysis/Delinearization/a.ll

 ; RUN: opt < %s -analyze -delinearize | FileCheck %s
 ;
 ; void foo(long n, long m, long o, int A[n][m][o]) {
 ;   for (long i = 0; i < n; i++)
 ;     for (long j = 0; j < m; j++)
 ;       for (long k = 0; k < o; k++)
 ;         A[2*i+3][3*j-4][5*k+7] = 1;
 ; }
 
 ; AddRec: {{{(28 + (4 * (-4 + (3 * %m)) * %o) + %A),+,(8 * %m * %o)}<%for.i>,+,(12 * %o)}<%for.j>,+,20}<%for.k>
 ; CHECK: Base offset: %A
 ; CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of 4 bytes.
-; CHECK: ArrayRef[{3,+,2}<%for.i>][{-4,+,3}<nw><%for.j>][{7,+,5}<nw><%for.k>]
+; CHECK: ArrayRef[{3,+,2}<nw><%for.i>][{-4,+,3}<nw><%for.j>][{7,+,5}<nw><%for.k>]
 
 define void @foo(i64 %n, i64 %m, i64 %o, i32* nocapture %A) #0 {
 entry:
   %cmp32 = icmp sgt i64 %n, 0
   br i1 %cmp32, label %for.cond1.preheader.lr.ph, label %for.end17
 
 for.cond1.preheader.lr.ph:                        ; preds = %entry
   %cmp230 = icmp sgt i64 %m, 0

llvm/trunk/test/Analysis/Delinearization/iv_times_constant_in_subscript.ll

 ; RUN: opt < %s -analyze -delinearize | FileCheck %s
 
 ; Derived from the following code:
 ;
 ; void foo(long n, long m, long b, double A[n][m]) {
 ;   for (long i = 0; i < n; i++)
 ;     for (long j = 0; j < m; j++)
 ;       A[2i+b][2j] = 1.0;
 ; }
 
 ; AddRec: {{((%m * %b * 8) + %A),+,(2 * %m * 8)}<%for.i>,+,(2 * 8)}<%for.j>
 ; CHECK: Base offset: %A
 ; CHECK: ArrayDecl[UnknownSize][%m] with elements of 8 bytes.
-; CHECK: ArrayRef[{%b,+,2}<nsw><%for.i>][{0,+,2}<%for.j>]
+; CHECK: ArrayRef[{%b,+,2}<nsw><%for.i>][{0,+,2}<nuw><%for.j>]
 
 
 define void @foo(i64 %n, i64 %m, i64 %b, double* %A) {
 entry:
   br label %for.i
 
 for.i:
   %i = phi i64 [ 0, %entry ], [ %i.inc, %for.i.inc ]

llvm/trunk/test/Analysis/IVUsers/quadradic-exit-value.ll

 ; PR15470: LSR miscompile. The test2 function should return '1'.
 ; It is illegal to fold SCEVUnknown (sext.us) into the recurrence
 ; because it is defined after the loop where this recurrence belongs.
 ;
 ; SCEV does not know how to denormalize chained recurrences, so make
 ; sure they aren't marked as post-inc users.
 ;
 ; CHECK-LABEL: IV Users for loop %test2.loop
-; CHECK-NO-LCSSA: %sub.cond.us = ((-1 * %sub.us)<nsw> + {0,+,1}<nuw><nsw><%test2.loop>) (post-inc with loop %test2.loop) in    %sext.us = mul i32 %mul.us, %sub.cond.us
+; CHECK-NO-LCSSA: %sub.cond.us = ((-1 * %sub.us)<nuw><nsw> + {0,+,1}<nuw><nsw><%test2.loop>) (post-inc with loop %test2.loop) in    %sext.us = mul i32 %mul.us, %sub.cond.us
 define i32 @test2() {
 entry:
   br label %test2.loop
 
 test2.loop:
   %inc1115.us = phi i32 [ 0, %entry ], [ %inc11.us, %test2.loop ]
   %inc11.us = add nsw i32 %inc1115.us, 1
   %cmp.us = icmp slt i32 %inc11.us, 2

llvm/trunk/test/Analysis/LoopAccessAnalysis/number-of-memchecks.ll

 ; CHECK-NEXT:     Against group ([[TWO:.+]]):
 ; CHECK-NEXT:       %arrayidxA2 = getelementptr i16, i16* %a, i64 %ind2
 ; CHECK-NEXT:   Grouped accesses:
 ; CHECK-NEXT:     Group {{.*}}[[ZERO]]:
 ; CHECK-NEXT:       (Low: ((2 * %offset) + %a)<nsw> High: (10000 + (2 * %offset) + %a))
 ; CHECK-NEXT:         Member: {((2 * %offset) + %a)<nsw>,+,2}<nsw><%for.body>
 ; CHECK-NEXT:     Group {{.*}}[[ONE]]:
 ; CHECK-NEXT:       (Low: %a High: (10000 + %a))
-; CHECK-NEXT:         Member: {%a,+,2}<%for.body>
+; CHECK-NEXT:         Member: {%a,+,2}<nw><%for.body>
 ; CHECK-NEXT:     Group {{.*}}[[TWO]]:
 ; CHECK-NEXT:       (Low: (20000 + %a) High: (30000 + %a))
-; CHECK-NEXT:         Member: {(20000 + %a),+,2}<%for.body>
+; CHECK-NEXT:         Member: {(20000 + %a),+,2}<nw><%for.body>
 
 define void @testi(i16* %a,
                    i64 %offset) {
 entry:
   br label %for.body
 
 for.body:                                         ; preds = %for.body, %entry
   %ind = phi i64 [ 0, %entry ], [ %add, %for.body ]

llvm/trunk/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll

 ; LAA-NEXT: {%a,+,4}<%for.body> Added Flags: <nusw>
 
 ; The expression for %mul_ext as analyzed by SCEV is
 ;    (zext i32 {0,+,2}<%for.body> to i64)
 ; We have added the nusw flag to turn this expression into the SCEV expression:
 ;    i64 {0,+,2}<%for.body>
 
 ; LAA: [PSE]  %arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext:
-; LAA-NEXT: ((2 * (zext i32 {0,+,2}<%for.body> to i64)) + %a)
+; LAA-NEXT: ((2 * (zext i32 {0,+,2}<%for.body> to i64))<nuw> + %a)
 ; LAA-NEXT: --> {%a,+,4}<%for.body>
 
 
 ; LV-LABEL: f1
 ; LV-LABEL: for.body.lver.check
 
 ; LV:      [[BETrunc:%[^ ]*]] = trunc i64 [[BE:%[^ ]*]] to i32
 ; LV-NEXT: [[OFMul:%[^ ]*]] = call { i32, i1 } @llvm.umul.with.overflow.i32(i32 2, i32 [[BETrunc]])

 ;
 ; This loop has a negative stride for A, and the nusw flag is required in
 ; order to properly extend the increment from i32 -4 to i64 -4.
 
 ; LAA-LABEL: f2
 ; LAA: Memory dependences are safe{{$}}
 ; LAA: SCEV assumptions:
 ; LAA-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nusw>
-; LAA-NEXT: {((2 * (zext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body> Added Flags: <nusw>
+; LAA-NEXT: {((2 * (zext i32 (2 * (trunc i64 %N to i32)) to i64))<nuw> + %a),+,-4}<%for.body> Added Flags: <nusw>
 
 ; The expression for %mul_ext as analyzed by SCEV is
 ;     (zext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64)
 ; We have added the nusw flag to turn this expression into the following SCEV:
 ;     i64 {zext i32 (2 * (trunc i64 %N to i32)) to i64,+,-2}<%for.body>
 
 ; LAA: [PSE]  %arrayidxA = getelementptr i16, i16* %a, i64 %mul_ext:
-; LAA-NEXT: ((2 * (zext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64)) + %a)
-; LAA-NEXT: --> {((2 * (zext i32 (2 * (trunc i64 %N to i32)) to i64)) + %a),+,-4}<%for.body>
+; LAA-NEXT: ((2 * (zext i32 {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> to i64))<nuw> + %a)
+; LAA-NEXT: --> {((2 * (zext i32 (2 * (trunc i64 %N to i32)) to i64))<nuw> + %a),+,-4}<%for.body>
 
 ; LV-LABEL: f2
 ; LV-LABEL: for.body.lver.check
 
 ; LV: [[OFMul:%[^ ]*]] = call { i32, i1 } @llvm.umul.with.overflow.i32(i32 2, i32 [[BETrunc:%[^ ]*]])
 ; LV-NEXT: [[OFMulResult:%[^ ]*]] = extractvalue { i32, i1 } [[OFMul]], 0
 ; LV-NEXT: [[OFMulOverflow:%[^ ]*]] = extractvalue { i32, i1 } [[OFMul]], 1
 ; LV-NEXT: [[AddEnd:%[^ ]*]] = add i32 [[Start:%[^ ]*]], [[OFMulResult]]

llvm/trunk/test/Analysis/ScalarEvolution/different-loops-recs.ll

 ; Demonstrate a situation when we can add two recs with different degrees from
 ; the same loop.
 define void @test_05(i32 %N) {
 
 ; CHECK-LABEL: Classifying expressions for: @test_05
 ; CHECK:       %SQ = mul i32 %i.0, %i.0
 ; CHECK-NEXT:  -->  {4,+,5,+,2}<%bb3>
 ; CHECK:       %tmp4 = mul i32 %i.0, 2
-; CHECK-NEXT:  -->  {4,+,2}<%bb3>
+; CHECK-NEXT:  -->  {4,+,2}<nuw><%bb3>
 ; CHECK:       %tmp5 = sub i32 %SQ, %tmp4
 ; CHECK-NEXT:  -->  {0,+,3,+,2}<%bb3>
 
 entry:
         %"alloca point" = bitcast i32 0 to i32           ; <i32> [#uses=0]
         br label %bb3
 
 bb:             ; preds = %bb3

llvm/trunk/test/Analysis/ScalarEvolution/mul-nuw.ll

+; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
+
+; Check that we add nuw to multiplies by a constant where we can infer that the
+; multiply does not have unsigned overflow.
+declare i32 @get_int();
+
+define void @foo() {
+  %a = call i32 @get_int(), !range !0
+  %b = mul i32 %a, 4
+  ; CHECK: %b
+  ; CHECK-NEXT: --> (4 * %a)<nuw>
+  ret void
+}
+
+!0 = !{i32 0, i32 100}

llvm/trunk/test/Analysis/ScalarEvolution/nsw-offset-assume.ll

 return:                                           ; preds = %bb1.return_crit_edge, %entry
   ret void
 }
 
 declare void @llvm.assume(i1) nounwind
 
 ; Note: Without the preheader assume, there is an 'smax' in the
 ; backedge-taken count expression:
-; CHECK: Loop %bb: backedge-taken count is ((-1 + (2 * (%no /u 2))) /u 2)
+; CHECK: Loop %bb: backedge-taken count is ((-1 + (2 * (%no /u 2))<nuw>) /u 2)
 ; CHECK: Loop %bb: max backedge-taken count is 1073741822

llvm/trunk/test/Analysis/ScalarEvolution/nsw-offset.ll

 
 bb1.return_crit_edge:                             ; preds = %bb1
   br label %return
 
 return:                                           ; preds = %bb1.return_crit_edge, %entry
   ret void
 }
 
-; CHECK: Loop %bb: backedge-taken count is ((-1 + (2 * (%no /u 2))) /u 2)
+; CHECK: Loop %bb: backedge-taken count is ((-1 + (2 * (%no /u 2))<nuw>) /u 2)
 ; CHECK: Loop %bb: max backedge-taken count is 1073741822

llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll

 ; CHECK-NEXT: -->  {0,+,1}<nuw><nsw><%bb>
   %tmp2 = sext i32 %i.01 to i64   ; <i64> [#uses=1]
   %tmp3 = getelementptr double, double* %p, i64 %tmp2    ; <double*> [#uses=1]
   %tmp4 = load double, double* %tmp3, align 8    ; <double> [#uses=1]
   %tmp5 = fmul double %tmp4, 9.200000e+00   ; <double> [#uses=1]
   %tmp6 = sext i32 %i.01 to i64   ; <i64> [#uses=1]
   %tmp7 = getelementptr double, double* %p, i64 %tmp6    ; <double*> [#uses=1]
 ; CHECK: %tmp7
-; CHECK-NEXT:   -->  {%p,+,8}<%bb>
+; CHECK-NEXT:   -->  {%p,+,8}<nw><%bb>
   store double %tmp5, double* %tmp7, align 8
   %tmp8 = add nsw i32 %i.01, 1    ; <i32> [#uses=2]
 ; CHECK: %tmp8
 ; CHECK-NEXT: -->  {1,+,1}<nuw><nsw><%bb>
   %p.gep = getelementptr double, double* %p, i32 %tmp8
   %p.val = load double, double* %p.gep
   br label %bb1
 
greater:
   br label %exit
 
 exit:
   %result = phi i32 [ %a, %entry ], [ %tmp2, %greater ]
   ret i32 %result
 }
 
 ; CHECK-LABEL: PR12375
-; CHECK: -->  {(4 + %arg)<nsw>,+,4}<nuw><%bb1>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg)<nsw> umax (8 + %arg)<nsw>)) /u 4)) + %arg)
+; CHECK: -->  {(4 + %arg)<nsw>,+,4}<nuw><%bb1>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg)<nsw> umax (8 + %arg)<nsw>)) /u 4))<nuw> + %arg)
 define i32 @PR12375(i32* readnone %arg) {
 bb:
   %tmp = getelementptr inbounds i32, i32* %arg, i64 2
   br label %bb1
 
 bb1:                                              ; preds = %bb1, %bb
   %tmp2 = phi i32* [ %arg, %bb ], [ %tmp5, %bb1 ]
   %tmp3 = phi i32 [ 0, %bb ], [ %tmp4, %bb1 ]
   %tmp4 = add nsw i32 %tmp3, 1
   %tmp5 = getelementptr inbounds i32, i32* %tmp2, i64 1
   %tmp6 = icmp ult i32* %tmp5, %tmp
   br i1 %tmp6, label %bb1, label %bb7
 
 bb7:                                              ; preds = %bb1
   ret i32 %tmp4
 }
 
 ; CHECK-LABEL: PR12376
-; CHECK: -->  {(4 + %arg)<nsw>,+,4}<nuw><%bb2>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg)<nsw> umax %arg1)) /u 4)) + %arg)
+; CHECK: -->  {(4 + %arg)<nsw>,+,4}<nuw><%bb2>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg)<nsw> umax %arg1)) /u 4))<nuw> + %arg)
 define void @PR12376(i32* nocapture %arg, i32* nocapture %arg1)  {
 bb:
   br label %bb2
 
 bb2:                                              ; preds = %bb2, %bb
   %tmp = phi i32* [ %arg, %bb ], [ %tmp4, %bb2 ]
   %tmp4 = getelementptr inbounds i32, i32* %tmp, i64 1
   %tmp3 = icmp ult i32* %tmp4, %arg1

llvm/trunk/test/Analysis/ScalarEvolution/sext-mul.ll

 ; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
 
 ; CHECK: %tmp9 = shl i64 %tmp8, 33
-; CHECK-NEXT: --> {{.*}} Exits: (-8589934592 + (8589934592 * (zext i32 %arg2 to i64)))
+; CHECK-NEXT: --> {{.*}} Exits: (-8589934592 + (8589934592 * (zext i32 %arg2 to i64))<nuw>)
 ; CHECK: %tmp10 = ashr exact i64 %tmp9, 32
 ; CHECK-NEXT: --> {{.*}} Exits: (sext i32 (-2 + (2 * %arg2)) to i64)
 ; CHECK: %tmp11 = getelementptr inbounds i32, i32* %arg, i64 %tmp10
 ; CHECK-NEXT: --> {{.*}} Exits: ((4 * (sext i32 (-2 + (2 * %arg2)) to i64)) + %arg)
 ; CHECK:  %tmp14 = or i64 %tmp10, 1
 ; CHECK-NEXT: --> {{.*}} Exits: (1 + (sext i32 (-2 + (2 * %arg2)) to i64))<nsw>
 ; CHECK: %tmp15 = getelementptr inbounds i32, i32* %arg, i64 %tmp14
 ; CHECK-NEXT: --> {{.*}} Exits: (4 + (4 * (sext i32 (-2 + (2 * %arg2)) to i64)) + %arg)
bb7:                                              ; preds = %bb7, %bb3
   %tmp17 = mul nsw i32 %tmp16, %arg1
   store i32 %tmp17, i32* %tmp15, align 4
   %tmp18 = add nuw nsw i64 %tmp8, 1
   %tmp19 = icmp eq i64 %tmp18, %tmp4
   br i1 %tmp19, label %bb5, label %bb7
 }
 
 ; CHECK: %t10 = ashr exact i128 %t9, 1
-; CHECK-NEXT: --> {{.*}} Exits: (sext i127 (-633825300114114700748351602688 + (633825300114114700748351602688 * (zext i32 %arg5 to i127))) to i128)
+; CHECK-NEXT: --> {{.*}} Exits: (sext i127 (-633825300114114700748351602688 + (633825300114114700748351602688 * (zext i32 %arg5 to i127))<nuw>) to i128)
 ; CHECK: %t14 = or i128 %t10, 1
-; CHECK-NEXT: --> {{.*}} Exits: (1 + (sext i127 (-633825300114114700748351602688 + (633825300114114700748351602688 * (zext i32 %arg5 to i127))) to i128))<nsw>
+; CHECK-NEXT: --> {{.*}} Exits: (1 + (sext i127 (-633825300114114700748351602688 + (633825300114114700748351602688 * (zext i32 %arg5 to i127))<nuw>) to i128))<nsw>
 ; CHECK: Loop %bb7: backedge-taken count is (-1 + (zext i32 %arg5 to i128))<nsw>
 ; CHECK-NEXT: Loop %bb7: max backedge-taken count is -1
 ; CHECK-NEXT: Loop %bb7: Predicated backedge-taken count is (-1 + (zext i32 %arg5 to i128))<nsw>
 
 define void @goo(i32* nocapture %arg3, i32 %arg4, i32 %arg5) {
 bb:
   %t = icmp sgt i32 %arg5, 0
   br i1 %t, label %bb3, label %bb6

llvm/trunk/test/Analysis/ScalarEvolution/sext-zero.ll

 ; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
 
 ; CHECK:  %tmp9 = shl i64 %tmp8, 33
-; CHECK-NEXT:  -->  {{.*}} Exits: (-8589934592 + (8589934592 * (zext i32 %arg2 to i64)))
+; CHECK-NEXT:  -->  {{.*}} Exits: (-8589934592 + (8589934592 * (zext i32 %arg2 to i64))<nuw>)
 ; CHECK-NEXT:  %tmp10 = ashr exact i64 %tmp9, 0
-; CHECK-NEXT:  -->  {{.*}} Exits: (-8589934592 + (8589934592 * (zext i32 %arg2 to i64)))
+; CHECK-NEXT:  -->  {{.*}} Exits: (-8589934592 + (8589934592 * (zext i32 %arg2 to i64))<nuw>)
 
 define void @foo(i32* nocapture %arg, i32 %arg1, i32 %arg2) {
 bb:
   %tmp = icmp sgt i32 %arg2, 0
   br i1 %tmp, label %bb3, label %bb6
 
 bb3:                                              ; preds = %bb
   %tmp4 = zext i32 %arg2 to i64

llvm/trunk/test/Analysis/ScalarEvolution/trip-count-pow2.ll

loop:
   %i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
   %i.next = add i32 %i, 32
   %t = icmp ne i32 %i.next, %s
   br i1 %t, label %loop, label %exit
 exit:
   ret i32 %i
 
 ; CHECK-LABEL: @test2
-; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * (%n /u 32))) /u 32)
+; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * (%n /u 32))<nuw>) /u 32)
 ; CHECK: Loop %loop: max backedge-taken count is 134217727
 }
 
 define void @test3(i32 %n) {
 entry:
   %s = mul i32 %n, 96
   br label %loop
 loop:

llvm/trunk/test/Transforms/IndVarSimplify/2011-09-10-widen-nsw.ll

for.body11:                                       ; preds = %entry
   br label %for.body153
 
 for.body153:                                      ; preds = %for.body153, %for.body11
   br i1 undef, label %for.body170, label %for.body153
 
 ; CHECK: add nuw nsw i64 %indvars.iv, 1
 ; CHECK: sub nsw i64 %indvars.iv, 2
 ; CHECK: sub nsw i64 4, %indvars.iv
-; CHECK: mul nsw i64 %indvars.iv, 8
+; CHECK: mul nuw nsw i64 %indvars.iv, 8
 for.body170:                                      ; preds = %for.body170, %for.body153
   %i2.19 = phi i32 [ %add249, %for.body170 ], [ 0, %for.body153 ]
 
   %add = add nsw i32 %i2.19, 1
   %add.idxprom = sext i32 %add to i64
 
   %sub = sub nsw i32 %i2.19, 2
   %sub.idxprom = sext i32 %sub to i64