diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 1a15bea0d922..6c8865915da9 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -17024,6 +17024,15 @@ static SDValue PerformSELECTCombine(SDNode *N, SelectionDAG &DAG, if (BitWidth == 1) return SDValue(); + // Check all uses of that condition operand to check whether it will be + // consumed by non-BLEND instructions, which may depend on all bits are set + // properly. + for (SDNode::use_iterator I = Cond->use_begin(), + E = Cond->use_end(); I != E; ++I) + if (I->getOpcode() != ISD::VSELECT) + // TODO: Add other opcodes eventually lowered into BLEND. + return SDValue(); + assert(BitWidth >= 8 && BitWidth <= 64 && "Invalid mask size"); APInt DemandedMask = APInt::getHighBitsSet(BitWidth, 1); diff --git a/llvm/test/CodeGen/X86/pr18014.ll b/llvm/test/CodeGen/X86/pr18014.ll new file mode 100644 index 000000000000..e3860b88bf4f --- /dev/null +++ b/llvm/test/CodeGen/X86/pr18014.ll @@ -0,0 +1,16 @@ +; RUN: llc < %s -mtriple=x86_64-linux-pc -mcpu=penryn | FileCheck %s + +; Ensure PSRAD is generated as the condition is consumed by both PADD and +; BLENDVPS. PAND requires all bits setting properly. + +define <4 x i32> @foo(<4 x i32>* %p, <4 x i1> %cond, <4 x i32> %v1, <4 x i32> %v2, <4 x i32> %v3) { + %sext_cond = sext <4 x i1> %cond to <4 x i32> + %t1 = add <4 x i32> %v1, %sext_cond + %t2 = select <4 x i1> %cond, <4 x i32> %v1, <4 x i32> %v2 + store <4 x i32> %t2, <4 x i32>* %p + ret <4 x i32> %t1 +; CHECK: foo +; CHECK: pslld +; CHECK: psrad +; CHECK: ret +}