[DAGCombine] optimizeSetCCOfSignedTruncationCheck(): handle inverted pattern

[lebedev.ri]

Summary

A follow-up for D49266 / rL337166 + D49497 / rL338044.

I'm actually not quite sure about this, is it this simple?
https://rise4fun.com/Alive/BDV
https://rise4fun.com/Alive/n7Z

[spatel]

That is complicated/magical. :)
It would be good to put an example with fixed constants in the code comments where you do the inversion, so we can better grasp how the transform works with real numbers.
x86 diffs look neutral or better. Adding some more potential AArch64 reviewers to confirm the same on those tests.

[efriedma]

AArch64 test changes look fine.

test/CodeGen/AArch64/signed-truncation-check.ll

110

We should be able to optimize out the masking here, I think, but I guess that's orthogonal.

[lebedev.ri]

Add very basic example of the expected pattern as a comment.

[spatel]

LGTM

[lebedev.ri]

In D51532#1221558, @spatel wrote:

LGTM

Thank you for the review!

lib/CodeGen/SelectionDAG/TargetLowering.cpp

if (Cond == ISD::CondCode::SETULT) {
     NewCond = ISD::CondCode::SETNE;
     // But need to 'canonicalize' the constant.
     I1 += 1;
   } else if (Cond == ISD::CondCode::SETUGE) {
     NewCond = ISD::CondCode::SETNE;
   } else
     return SDValue();
 
-  const APInt &I01 = C01->getAPIntValue();
+  APInt I01 = C01->getAPIntValue();
+
+  auto checkConstants = [&I1, &I01]() -> bool {
     // Both of them must be power-of-two, and the constant from setcc is bigger.
-  if (!(I1.ugt(I01) && I1.isPowerOf2() && I01.isPowerOf2()))
+    return I1.ugt(I01) && I1.isPowerOf2() && I01.isPowerOf2();
+  };
+
+  if (checkConstants()) {
+    // Great.
+  } else {
+    // What if we invert constants? (and the target predicate)
+    I1.negate();
+    I01.negate();
+    NewCond = getSetCCInverse(NewCond, /*isInteger=*/true);
+    if (!checkConstants())
       return SDValue();
+  }
 
   // They are power-of-two, so which bit is set?
   const unsigned KeptBits = I1.logBase2();
   const unsigned KeptBitsMinusOne = I01.logBase2();
 
   // Magic!
   if (KeptBits != (KeptBitsMinusOne + 1))
     return SDValue();

test/CodeGen/AArch64/lack-of-signed-truncation-check.ll

 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp ult
 ; ---------------------------------------------------------------------------- ;
 
 define i1 @add_ultcmp_i16_i8(i16 %x) nounwind {
 ; CHECK-LABEL: add_ultcmp_i16_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #128 // =128
-; CHECK-NEXT:    ubfx w8, w8, #8, #8
-; CHECK-NEXT:    cmp w8, #255 // =255
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxtb w8, w0
+; CHECK-NEXT:    and w8, w8, #0xffff
+; CHECK-NEXT:    cmp w8, w0, uxth
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ult i16 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i32_i16(i32 %x) nounwind {
 ; CHECK-LABEL: add_ultcmp_i32_i16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #8, lsl #12 // =32768
-; CHECK-NEXT:    cmn w8, #16, lsl #12 // =65536
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxth w8, w0
+; CHECK-NEXT:    cmp w8, w0
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i32 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp ult i32 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i32_i8(i32 %x) nounwind {
 ; CHECK-LABEL: add_ultcmp_i32_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #128 // =128
-; CHECK-NEXT:    cmn w8, #256 // =256
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxtb w8, w0
+; CHECK-NEXT:    cmp w8, w0
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i32 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ult i32 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i64_i32(i64 %x) nounwind {
 ; CHECK-LABEL: add_ultcmp_i64_i32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    mov x8, #-2147483648
-; CHECK-NEXT:    add x8, x0, x8
-; CHECK-NEXT:    mov x9, #-4294967296
-; CHECK-NEXT:    cmp x8, x9
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxtw x8, w0
+; CHECK-NEXT:    cmp x8, x0
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i64 %x, -2147483648 ; ~0U << (32-1)
   %tmp1 = icmp ult i64 %tmp0, -4294967296 ; ~0U << 32
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i64_i16(i64 %x) nounwind {
 ; CHECK-LABEL: add_ultcmp_i64_i16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub x8, x0, #8, lsl #12 // =32768
-; CHECK-NEXT:    cmn x8, #16, lsl #12 // =65536
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxth x8, w0
+; CHECK-NEXT:    cmp x8, x0
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i64 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp ult i64 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i64_i8(i64 %x) nounwind {
 ; CHECK-LABEL: add_ultcmp_i64_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub x8, x0, #128 // =128
-; CHECK-NEXT:    cmn x8, #256 // =256
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxtb x8, w0
+; CHECK-NEXT:    cmp x8, x0
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i64 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ult i64 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 ; Slightly more canonical variant
 define i1 @add_ulecmp_i16_i8(i16 %x) nounwind {
 ; CHECK-LABEL: add_ulecmp_i16_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #128 // =128
-; CHECK-NEXT:    ubfx w8, w8, #8, #8
-; CHECK-NEXT:    cmp w8, #255 // =255
-; CHECK-NEXT:    cset w0, lo
+; CHECK-NEXT:    sxtb w8, w0
+; CHECK-NEXT:    and w8, w8, #0xffff
+; CHECK-NEXT:    cmp w8, w0, uxth
+; CHECK-NEXT:    cset w0, ne
 ; CHECK-NEXT:    ret
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ule i16 %tmp0, -257 ; ~0U << 8 - 1
   ret i1 %tmp1
 }
 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp uge

test/CodeGen/AArch64/signed-truncation-check.ll

 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp uge
 ; ---------------------------------------------------------------------------- ;
 
 define i1 @add_ugecmp_i16_i8(i16 %x) nounwind {
 ; CHECK-LABEL: add_ugecmp_i16_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #128 // =128
-; CHECK-NEXT:    ubfx w8, w8, #8, #8
-; CHECK-NEXT:    cmp w8, #254 // =254
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxtb w8, w0
+; CHECK-NEXT:    and w8, w8, #0xffff
+; CHECK-NEXT:    cmp w8, w0, uxth
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp uge i16 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i32_i16(i32 %x) nounwind {
 ; CHECK-LABEL: add_ugecmp_i32_i16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #8, lsl #12 // =32768
-; CHECK-NEXT:    orr w9, wzr, #0xfffeffff
-; CHECK-NEXT:    cmp w8, w9
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxth w8, w0
+; CHECK-NEXT:    cmp w8, w0
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i32 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp uge i32 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i32_i8(i32 %x) nounwind {
 ; CHECK-LABEL: add_ugecmp_i32_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #128 // =128
-; CHECK-NEXT:    cmn w8, #257 // =257
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxtb w8, w0
+; CHECK-NEXT:    cmp w8, w0
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i32 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp uge i32 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i64_i32(i64 %x) nounwind {
 ; CHECK-LABEL: add_ugecmp_i64_i32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    mov x8, #-2147483648
-; CHECK-NEXT:    add x8, x0, x8
-; CHECK-NEXT:    orr x9, xzr, #0xfffffffeffffffff
-; CHECK-NEXT:    cmp x8, x9
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxtw x8, w0
+; CHECK-NEXT:    cmp x8, x0
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i64 %x, -2147483648 ; ~0U << (32-1)
   %tmp1 = icmp uge i64 %tmp0, -4294967296 ; ~0U << 32
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i64_i16(i64 %x) nounwind {
 ; CHECK-LABEL: add_ugecmp_i64_i16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub x8, x0, #8, lsl #12 // =32768
-; CHECK-NEXT:    orr x9, xzr, #0xfffffffffffeffff
-; CHECK-NEXT:    cmp x8, x9
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxth x8, w0
+; CHECK-NEXT:    cmp x8, x0
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i64 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp uge i64 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i64_i8(i64 %x) nounwind {
 ; CHECK-LABEL: add_ugecmp_i64_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub x8, x0, #128 // =128
-; CHECK-NEXT:    cmn x8, #257 // =257
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxtb x8, w0
+; CHECK-NEXT:    cmp x8, x0
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i64 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp uge i64 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 ; Slightly more canonical variant
 define i1 @add_ugtcmp_i16_i8(i16 %x) nounwind {
 ; CHECK-LABEL: add_ugtcmp_i16_i8:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    sub w8, w0, #128 // =128
-; CHECK-NEXT:    ubfx w8, w8, #8, #8
-; CHECK-NEXT:    cmp w8, #254 // =254
-; CHECK-NEXT:    cset w0, hi
+; CHECK-NEXT:    sxtb w8, w0
+; CHECK-NEXT:    and w8, w8, #0xffff
+; CHECK-NEXT:    cmp w8, w0, uxth
+; CHECK-NEXT:    cset w0, eq
 ; CHECK-NEXT:    ret
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ugt i16 %tmp0, -257 ; ~0U << 8 - 1
   ret i1 %tmp1
 }
 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp ult

test/CodeGen/X86/lack-of-signed-truncation-check.ll

 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp ult
 ; ---------------------------------------------------------------------------- ;
 
 define i1 @add_ultcmp_i16_i8(i16 %x) nounwind {
 ; X86-LABEL: add_ultcmp_i16_i8:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    movzwl %ax, %eax
-; X86-NEXT:    cmpl $65280, %eax # imm = 0xFF00
-; X86-NEXT:    setb %al
+; X86-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    cmpw %ax, %cx
+; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ultcmp_i16_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-128, %edi
-; X64-NEXT:    movzwl %di, %eax
-; X64-NEXT:    cmpl $65280, %eax # imm = 0xFF00
-; X64-NEXT:    setb %al
+; X64-NEXT:    movsbl %dil, %eax
+; X64-NEXT:    cmpw %di, %ax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ult i16 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i32_i16(i32 %x) nounwind {
 ; X86-LABEL: add_ultcmp_i32_i16:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl $-32768, %eax # imm = 0x8000
-; X86-NEXT:    addl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    cmpl $-65536, %eax # imm = 0xFFFF0000
-; X86-NEXT:    setb %al
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movswl %ax, %ecx
+; X86-NEXT:    cmpl %eax, %ecx
+; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ultcmp_i32_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-32768, %edi # imm = 0x8000
-; X64-NEXT:    cmpl $-65536, %edi # imm = 0xFFFF0000
-; X64-NEXT:    setb %al
+; X64-NEXT:    movswl %di, %eax
+; X64-NEXT:    cmpl %edi, %eax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i32 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp ult i32 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i32_i8(i32 %x) nounwind {
 ; X86-LABEL: add_ultcmp_i32_i8:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    cmpl $-256, %eax
-; X86-NEXT:    setb %al
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    cmpl %eax, %ecx
+; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ultcmp_i32_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-128, %edi
-; X64-NEXT:    cmpl $-256, %edi
-; X64-NEXT:    setb %al
+; X64-NEXT:    movsbl %dil, %eax
+; X64-NEXT:    cmpl %edi, %eax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i32 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ult i32 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i64_i32(i64 %x) nounwind {
 ; X86-LABEL: add_ultcmp_i64_i32:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl $-2147483648, %ecx # imm = 0x80000000
-; X86-NEXT:    addl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    adcl $-1, %eax
-; X86-NEXT:    cmpl $-1, %eax
+; X86-NEXT:    sarl $31, %eax
+; X86-NEXT:    xorl {{[0-9]+}}(%esp), %eax
 ; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ultcmp_i64_i32:
 ; X64:       # %bb.0:
-; X64-NEXT:    addq $-2147483648, %rdi # imm = 0x80000000
-; X64-NEXT:    movabsq $-4294967296, %rax # imm = 0xFFFFFFFF00000000
-; X64-NEXT:    cmpq %rax, %rdi
-; X64-NEXT:    setb %al
+; X64-NEXT:    movslq %edi, %rax
+; X64-NEXT:    cmpq %rdi, %rax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i64 %x, -2147483648 ; ~0U << (32-1)
   %tmp1 = icmp ult i64 %tmp0, -4294967296 ; ~0U << 32
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i64_i16(i64 %x) nounwind {
 ; X86-LABEL: add_ultcmp_i64_i16:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl $-32768, %ecx # imm = 0x8000
-; X86-NEXT:    addl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    adcl $-1, %eax
-; X86-NEXT:    cmpl $-65536, %ecx # imm = 0xFFFF0000
-; X86-NEXT:    sbbl $-1, %eax
-; X86-NEXT:    setb %al
+; X86-NEXT:    movswl %ax, %ecx
+; X86-NEXT:    xorl %ecx, %eax
+; X86-NEXT:    sarl $31, %ecx
+; X86-NEXT:    xorl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    orl %eax, %ecx
+; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ultcmp_i64_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    addq $-32768, %rdi # imm = 0x8000
-; X64-NEXT:    cmpq $-65536, %rdi # imm = 0xFFFF0000
-; X64-NEXT:    setb %al
+; X64-NEXT:    movswq %di, %rax
+; X64-NEXT:    cmpq %rdi, %rax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i64 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp ult i64 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ultcmp_i64_i8(i64 %x) nounwind {
 ; X86-LABEL: add_ultcmp_i64_i8:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    adcl $-1, %ecx
-; X86-NEXT:    cmpl $-256, %eax
-; X86-NEXT:    sbbl $-1, %ecx
-; X86-NEXT:    setb %al
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    xorl %ecx, %eax
+; X86-NEXT:    sarl $31, %ecx
+; X86-NEXT:    xorl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    orl %eax, %ecx
+; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ultcmp_i64_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addq $-128, %rdi
-; X64-NEXT:    cmpq $-256, %rdi
-; X64-NEXT:    setb %al
+; X64-NEXT:    movsbq %dil, %rax
+; X64-NEXT:    cmpq %rdi, %rax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i64 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ult i64 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 ; Slightly more canonical variant
 define i1 @add_ulecmp_i16_i8(i16 %x) nounwind {
 ; X86-LABEL: add_ulecmp_i16_i8:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    movzwl %ax, %eax
-; X86-NEXT:    cmpl $65280, %eax # imm = 0xFF00
-; X86-NEXT:    setb %al
+; X86-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    cmpw %ax, %cx
+; X86-NEXT:    setne %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ulecmp_i16_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-128, %edi
-; X64-NEXT:    movzwl %di, %eax
-; X64-NEXT:    cmpl $65280, %eax # imm = 0xFF00
-; X64-NEXT:    setb %al
+; X64-NEXT:    movsbl %dil, %eax
+; X64-NEXT:    cmpw %di, %ax
+; X64-NEXT:    setne %al
 ; X64-NEXT:    retq
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ule i16 %tmp0, -257 ; ~0U << 8 - 1
   ret i1 %tmp1
 }
 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp uge

test/CodeGen/X86/signed-truncation-check.ll

 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp uge
 ; ---------------------------------------------------------------------------- ;
 
 define i1 @add_ugecmp_i16_i8(i16 %x) nounwind {
 ; X86-LABEL: add_ugecmp_i16_i8:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    movzwl %ax, %eax
-; X86-NEXT:    cmpl $65279, %eax # imm = 0xFEFF
-; X86-NEXT:    seta %al
+; X86-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    cmpw %ax, %cx
+; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugecmp_i16_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-128, %edi
-; X64-NEXT:    movzwl %di, %eax
-; X64-NEXT:    cmpl $65279, %eax # imm = 0xFEFF
-; X64-NEXT:    seta %al
+; X64-NEXT:    movsbl %dil, %eax
+; X64-NEXT:    cmpw %di, %ax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp uge i16 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i32_i16(i32 %x) nounwind {
 ; X86-LABEL: add_ugecmp_i32_i16:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl $-32768, %eax # imm = 0x8000
-; X86-NEXT:    addl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    cmpl $-65537, %eax # imm = 0xFFFEFFFF
-; X86-NEXT:    seta %al
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movswl %ax, %ecx
+; X86-NEXT:    cmpl %eax, %ecx
+; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugecmp_i32_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-32768, %edi # imm = 0x8000
-; X64-NEXT:    cmpl $-65537, %edi # imm = 0xFFFEFFFF
-; X64-NEXT:    seta %al
+; X64-NEXT:    movswl %di, %eax
+; X64-NEXT:    cmpl %edi, %eax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i32 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp uge i32 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i32_i8(i32 %x) nounwind {
 ; X86-LABEL: add_ugecmp_i32_i8:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    cmpl $-257, %eax # imm = 0xFEFF
-; X86-NEXT:    seta %al
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    cmpl %eax, %ecx
+; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugecmp_i32_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-128, %edi
-; X64-NEXT:    cmpl $-257, %edi # imm = 0xFEFF
-; X64-NEXT:    seta %al
+; X64-NEXT:    movsbl %dil, %eax
+; X64-NEXT:    cmpl %edi, %eax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i32 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp uge i32 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i64_i32(i64 %x) nounwind {
 ; X86-LABEL: add_ugecmp_i64_i32:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl $-2147483648, %ecx # imm = 0x80000000
-; X86-NEXT:    addl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    adcl $-1, %eax
-; X86-NEXT:    cmpl $-1, %eax
+; X86-NEXT:    sarl $31, %eax
+; X86-NEXT:    xorl {{[0-9]+}}(%esp), %eax
 ; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugecmp_i64_i32:
 ; X64:       # %bb.0:
-; X64-NEXT:    addq $-2147483648, %rdi # imm = 0x80000000
-; X64-NEXT:    movabsq $-4294967297, %rax # imm = 0xFFFFFFFEFFFFFFFF
-; X64-NEXT:    cmpq %rax, %rdi
-; X64-NEXT:    seta %al
+; X64-NEXT:    movslq %edi, %rax
+; X64-NEXT:    cmpq %rdi, %rax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i64 %x, -2147483648 ; ~0U << (32-1)
   %tmp1 = icmp uge i64 %tmp0, -4294967296 ; ~0U << 32
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i64_i16(i64 %x) nounwind {
 ; X86-LABEL: add_ugecmp_i64_i16:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl $-32768, %ecx # imm = 0x8000
-; X86-NEXT:    addl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    adcl $-1, %eax
-; X86-NEXT:    movl $-65537, %edx # imm = 0xFFFEFFFF
-; X86-NEXT:    cmpl %ecx, %edx
-; X86-NEXT:    movl $-1, %ecx
-; X86-NEXT:    sbbl %eax, %ecx
-; X86-NEXT:    setb %al
+; X86-NEXT:    movswl %ax, %ecx
+; X86-NEXT:    xorl %ecx, %eax
+; X86-NEXT:    sarl $31, %ecx
+; X86-NEXT:    xorl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    orl %eax, %ecx
+; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugecmp_i64_i16:
 ; X64:       # %bb.0:
-; X64-NEXT:    addq $-32768, %rdi # imm = 0x8000
-; X64-NEXT:    cmpq $-65537, %rdi # imm = 0xFFFEFFFF
-; X64-NEXT:    seta %al
+; X64-NEXT:    movswq %di, %rax
+; X64-NEXT:    cmpq %rdi, %rax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i64 %x, -32768 ; ~0U << (16-1)
   %tmp1 = icmp uge i64 %tmp0, -65536 ; ~0U << 16
   ret i1 %tmp1
 }
 
 define i1 @add_ugecmp_i64_i8(i64 %x) nounwind {
 ; X86-LABEL: add_ugecmp_i64_i8:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    adcl $-1, %ecx
-; X86-NEXT:    movl $-257, %edx # imm = 0xFEFF
-; X86-NEXT:    cmpl %eax, %edx
-; X86-NEXT:    movl $-1, %eax
-; X86-NEXT:    sbbl %ecx, %eax
-; X86-NEXT:    setb %al
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    xorl %ecx, %eax
+; X86-NEXT:    sarl $31, %ecx
+; X86-NEXT:    xorl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    orl %eax, %ecx
+; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugecmp_i64_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addq $-128, %rdi
-; X64-NEXT:    cmpq $-257, %rdi # imm = 0xFEFF
-; X64-NEXT:    seta %al
+; X64-NEXT:    movsbq %dil, %rax
+; X64-NEXT:    cmpq %rdi, %rax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i64 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp uge i64 %tmp0, -256 ; ~0U << 8
   ret i1 %tmp1
 }
 
 ; Slightly more canonical variant
 define i1 @add_ugtcmp_i16_i8(i16 %x) nounwind {
 ; X86-LABEL: add_ugtcmp_i16_i8:
 ; X86:       # %bb.0:
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    addl $-128, %eax
-; X86-NEXT:    movzwl %ax, %eax
-; X86-NEXT:    cmpl $65279, %eax # imm = 0xFEFF
-; X86-NEXT:    seta %al
+; X86-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movsbl %al, %ecx
+; X86-NEXT:    cmpw %ax, %cx
+; X86-NEXT:    sete %al
 ; X86-NEXT:    retl
 ;
 ; X64-LABEL: add_ugtcmp_i16_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    addl $-128, %edi
-; X64-NEXT:    movzwl %di, %eax
-; X64-NEXT:    cmpl $65279, %eax # imm = 0xFEFF
-; X64-NEXT:    seta %al
+; X64-NEXT:    movsbl %dil, %eax
+; X64-NEXT:    cmpw %di, %ax
+; X64-NEXT:    sete %al
 ; X64-NEXT:    retq
   %tmp0 = add i16 %x, -128 ; ~0U << (8-1)
   %tmp1 = icmp ugt i16 %tmp0, -257 ; ~0U << 8 - 1
   ret i1 %tmp1
 }
 
 ; ---------------------------------------------------------------------------- ;
 ; add + icmp ult