diff options
| -rw-r--r-- | llvm/lib/Target/X86/X86TargetTransformInfo.cpp | 6 | ||||
| -rw-r--r-- | llvm/test/Transforms/ConstantHoisting/X86/bad-cases.ll | 47 |
2 files changed, 52 insertions, 1 deletions
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp index 4c14715b758..d3a75123935 100644 --- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp +++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp @@ -2342,11 +2342,15 @@ int X86TTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm, return TTI::TCC_Free; ImmIdx = 1; break; - case Instruction::Mul: case Instruction::UDiv: case Instruction::SDiv: case Instruction::URem: case Instruction::SRem: + // Division by constant is typically expanded later into a different + // instruction sequence. This completely changes the constants. + // Report them as "free" to stop ConstantHoist from marking them as opaque. + return TTI::TCC_Free; + case Instruction::Mul: case Instruction::Or: case Instruction::Xor: ImmIdx = 1; diff --git a/llvm/test/Transforms/ConstantHoisting/X86/bad-cases.ll b/llvm/test/Transforms/ConstantHoisting/X86/bad-cases.ll new file mode 100644 index 00000000000..00890942096 --- /dev/null +++ b/llvm/test/Transforms/ConstantHoisting/X86/bad-cases.ll @@ -0,0 +1,47 @@ +; RUN: opt -consthoist -S < %s | FileCheck %s +target triple = "x86_64--" + +; We don't want to convert constant divides because the benefit from converting +; them to a mul in the backend is larget than constant materialization savings. +define void @signed_const_division(i64 %in1, i64 %in2, i64* %addr) { +; CHECK-LABEL: @signed_const_division +; CHECK: %res1 = sdiv i64 %l1, 4294967296 +; CHECK: %res2 = srem i64 %l2, 4294967296 +entry: + br label %loop + +loop: + %l1 = phi i64 [%res1, %loop], [%in1, %entry] + %l2 = phi i64 [%res2, %loop], [%in2, %entry] + %res1 = sdiv i64 %l1, 4294967296 + store volatile i64 %res1, i64* %addr + %res2 = srem i64 %l2, 4294967296 + store volatile i64 %res2, i64* %addr + %again = icmp eq i64 %res1, %res2 + br i1 %again, label %loop, label %end + +end: + ret void +} + +define void @unsigned_const_division(i64 %in1, i64 %in2, i64* %addr) { +; CHECK-LABEL: @unsigned_const_division +; CHECK: %res1 = udiv i64 %l1, 4294967296 +; CHECK: %res2 = urem i64 %l2, 4294967296 + +entry: + br label %loop + +loop: + %l1 = phi i64 [%res1, %loop], [%in1, %entry] + %l2 = phi i64 [%res2, %loop], [%in2, %entry] + %res1 = udiv i64 %l1, 4294967296 + store volatile i64 %res1, i64* %addr + %res2 = urem i64 %l2, 4294967296 + store volatile i64 %res2, i64* %addr + %again = icmp eq i64 %res1, %res2 + br i1 %again, label %loop, label %end + +end: + ret void +} |
