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| author | Craig Topper <craig.topper@intel.com> | 2020-07-04 11:42:00 -0700 |
|---|---|---|
| committer | Craig Topper <craig.topper@intel.com> | 2020-07-04 11:42:53 -0700 |
| commit | 120c5f1057dc50229f73bc75bbabf4df6ee50fef (patch) | |
| tree | ce1b4a9ba2a453ef9972b0a1e18ba7e31fab41df | |
| parent | 21d8f66d20b813edadac84b12cc83b66eaeae630 (diff) | |
| download | llvm-120c5f1057dc50229f73bc75bbabf4df6ee50fef.zip llvm-120c5f1057dc50229f73bc75bbabf4df6ee50fef.tar.gz llvm-120c5f1057dc50229f73bc75bbabf4df6ee50fef.tar.bz2 | |
[DAGCombiner] Don't fold zext_vector_inreg/sext_vector_inreg(undef) to undef. Fold to 0.
zext_vector_inreg needs to produces 0s in the extended bits and
sext_vector_inreg needs to produce upper bits that are all the
same. So we should fold them to a 0 vector instead of undef.
Fixes PR46585.
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 6 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/pr46585.ll | 2 |
2 files changed, 5 insertions, 3 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index bd7d94e..c0d5337 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -11086,8 +11086,9 @@ SDValue DAGCombiner::visitSIGN_EXTEND_VECTOR_INREG(SDNode *N) { SDValue N0 = N->getOperand(0); EVT VT = N->getValueType(0); + // sext_vector_inreg(undef) = 0 because the top bit will all be the same. if (N0.isUndef()) - return DAG.getUNDEF(VT); + return DAG.getConstant(0, SDLoc(N), VT); if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes)) return Res; @@ -11102,8 +11103,9 @@ SDValue DAGCombiner::visitZERO_EXTEND_VECTOR_INREG(SDNode *N) { SDValue N0 = N->getOperand(0); EVT VT = N->getValueType(0); + // zext_vector_inreg(undef) = 0 because the top bits will be zero. if (N0.isUndef()) - return DAG.getUNDEF(VT); + return DAG.getConstant(0, SDLoc(N), VT); if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes)) return Res; diff --git a/llvm/test/CodeGen/X86/pr46585.ll b/llvm/test/CodeGen/X86/pr46585.ll index 65cd6b8..7bea631 100644 --- a/llvm/test/CodeGen/X86/pr46585.ll +++ b/llvm/test/CodeGen/X86/pr46585.ll @@ -7,7 +7,7 @@ define void @spam() local_unnamed_addr { ; CHECK-LABEL: spam: ; CHECK: ## %bb.0: ## %bb -; CHECK-NEXT: pmovmskb %xmm0, %eax +; CHECK-NEXT: xorl %eax, %eax ; CHECK-NEXT: testb %al, %al ; CHECK-NEXT: je LBB0_2 ; CHECK-NEXT: ## %bb.1: ## %bb9 |