Commit 5ff5cf8e authored by Craig Topper's avatar Craig Topper
Browse files

[X86] Use APInt::isSignedIntN instead of isIntN for 64-bit ANDs in... 

[X86] Use APInt::isSignedIntN instead of isIntN for 64-bit ANDs in X86DAGToDAGISel::IsProfitableToFold

Pretty sure we meant to be checking signed 32 immediates here
rather than unsigned 32 bit. I suspect I messed this up because
in MathExtras.h we have isIntN and isUIntN so isIntN differs in
signedness depending on whether you're using APInt or plain integers.

This fixes a case where we didn't fold a constant created
by shrinkAndImmediate. Since shrinkAndImmediate doesn't topologically
sort constants it creates, we can fail to convert the Constant
to a TargetConstant. This leads to very strange behavior later.

Fixes PR48458.
parent c8466a57

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

+1 −1
Original line number Diff line number Diff line
@@ -616,7 +616,7 @@ X86DAGToDAGISel::IsProfitableToFold(SDValue N, SDNode *U, SDNode *Root) const { 
        // best of both worlds.

        if (U->getOpcode() == ISD::AND &&

            Imm->getAPIntValue().getBitWidth() == 64 &&

            Imm->getAPIntValue().isIntN(32))

            Imm->getAPIntValue().isSignedIntN(32))

          return false;



        // If this really a zext_inreg that can be represented with a movzx

llvm/test/CodeGen/X86/pr48458.ll

0 → 100644
+17 −0
Original line number Diff line number Diff line 
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py

; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s



define i1 @foo(i64* %0) {

; CHECK-LABEL: foo:

; CHECK:       # %bb.0: # %top

; CHECK-NEXT:    movq (%rdi), %rax

; CHECK-NEXT:    andq $-2147483648, %rax # imm = 0x80000000

; CHECK-NEXT:    sete %al

; CHECK-NEXT:    retq

top:

  %1 = load i64, i64* %0, !range !0

  %2 = icmp ult i64 %1, 2147483648

  ret i1 %2

}



!0 = !{i64 0, i64 10000000000}