[llvm] r209902 - [pr19636] Fix known bit computation in urem instruction with power of two.
Rafael Espindola
rafael.espindola at gmail.com
Fri May 30 08:00:45 PDT 2014
Author: rafael
Date: Fri May 30 10:00:45 2014
New Revision: 209902
URL: http://llvm.org/viewvc/llvm-project?rev=209902&view=rev
Log:
[pr19636] Fix known bit computation in urem instruction with power of two.
Patch by Andrey Kuharev.
Added:
llvm/trunk/test/CodeGen/X86/computeKnownBits_urem.ll
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=209902&r1=209901&r2=209902&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Fri May 30 10:00:45 2014
@@ -2185,8 +2185,11 @@ void SelectionDAG::computeKnownBits(SDVa
const APInt &RA = Rem->getAPIntValue();
if (RA.isPowerOf2()) {
APInt LowBits = (RA - 1);
- KnownZero |= ~LowBits;
- computeKnownBits(Op.getOperand(0), KnownZero, KnownOne,Depth+1);
+ computeKnownBits(Op.getOperand(0), KnownZero2, KnownOne2, Depth + 1);
+
+ // The upper bits are all zero, the lower ones are unchanged.
+ KnownZero = KnownZero2 | ~LowBits;
+ KnownOne = KnownOne2 & LowBits;
break;
}
}
Added: llvm/trunk/test/CodeGen/X86/computeKnownBits_urem.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/computeKnownBits_urem.ll?rev=209902&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/computeKnownBits_urem.ll (added)
+++ llvm/trunk/test/CodeGen/X86/computeKnownBits_urem.ll Fri May 30 10:00:45 2014
@@ -0,0 +1,14 @@
+; RUN: llc -mtriple=x86_64-linux < %s | FileCheck %s
+define i32 @main() #0 {
+entry:
+ %a = alloca i32, align 4
+ store i32 1, i32* %a, align 4
+ %0 = load i32* %a, align 4
+ %or = or i32 1, %0
+ %and = and i32 1, %or
+ %rem = urem i32 %and, 1
+ %add = add i32 %rem, 1
+ ret i32 %add
+}
+; CHECK: $1, %eax
+; CHECK-NEXT: retq
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