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| author | Evan Cheng <evan.cheng@apple.com> | 2011-03-15 02:22:10 +0000 |
|---|---|---|
| committer | Evan Cheng <evan.cheng@apple.com> | 2011-03-15 02:22:10 +0000 |
| commit | c5c2cfa38114f7b71d1af3137d3d3afa4031d5de (patch) | |
| tree | 38244bea8465968f52d6e694829f3b6626646183 | |
| parent | 928de167936c1f0c9cf24cd467bcdcb6d61a64ab (diff) | |
| download | bcm5719-llvm-c5c2cfa38114f7b71d1af3137d3d3afa4031d5de.tar.gz bcm5719-llvm-c5c2cfa38114f7b71d1af3137d3d3afa4031d5de.zip | |
sext(undef) = 0, because the top bits will all be the same.
zext(undef) = 0, because the top bits will be zero.
llvm-svn: 127649
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 6 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/machine-cse.ll | 4 |
2 files changed, 7 insertions, 3 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index bcb0ffe3a5b..c2711c8097d 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -2483,7 +2483,8 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, if (OpOpcode == ISD::SIGN_EXTEND || OpOpcode == ISD::ZERO_EXTEND) return getNode(OpOpcode, DL, VT, Operand.getNode()->getOperand(0)); else if (OpOpcode == ISD::UNDEF) - return getUNDEF(VT); + // sext(undef) = 0, because the top bits will all be the same. + return getConstant(0, VT); break; case ISD::ZERO_EXTEND: assert(VT.isInteger() && Operand.getValueType().isInteger() && @@ -2498,6 +2499,9 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, if (OpOpcode == ISD::ZERO_EXTEND) // (zext (zext x)) -> (zext x) return getNode(ISD::ZERO_EXTEND, DL, VT, Operand.getNode()->getOperand(0)); + else if (OpOpcode == ISD::UNDEF) + // zext(undef) = 0, because the top bits will be zero. + return getConstant(0, VT); break; case ISD::ANY_EXTEND: assert(VT.isInteger() && Operand.getValueType().isInteger() && diff --git a/llvm/test/CodeGen/X86/machine-cse.ll b/llvm/test/CodeGen/X86/machine-cse.ll index e284776ed02..d819fc8f6ec 100644 --- a/llvm/test/CodeGen/X86/machine-cse.ll +++ b/llvm/test/CodeGen/X86/machine-cse.ll @@ -6,11 +6,11 @@ %struct.s2 = type { i32, i8*, i8*, [256 x %struct.s1*], [8 x i32], i64, i8*, i32, i64, i64, i32, %struct.s3*, %struct.s3*, [49 x i64] } %struct.s3 = type { %struct.s3*, %struct.s3*, i32, i32, i32 } -define fastcc i8* @t(i64 %size) nounwind { +define fastcc i8* @t(i32 %base) nounwind { entry: ; CHECK: t: ; CHECK: leaq (%rax,%rax,4) - %0 = zext i32 undef to i64 + %0 = zext i32 %base to i64 %1 = getelementptr inbounds %struct.s2* null, i64 %0 br i1 undef, label %bb1, label %bb2 |
