diff --git a/llvm/include/llvm/CodeGen/FastISel.h b/llvm/include/llvm/CodeGen/FastISel.h index 81c1d6aad49a1..26bf4ab2618ce 100644 --- a/llvm/include/llvm/CodeGen/FastISel.h +++ b/llvm/include/llvm/CodeGen/FastISel.h @@ -490,7 +490,10 @@ class FastISel { /// - \c Add has a constant operand. bool canFoldAddIntoGEP(const User *GEP, const Value *Add); - /// Test whether the given value has exactly one use. + /// Test whether the register associated with this value has exactly one use, + /// in which case that single use is killing. Note that multiple IR values + /// may map onto the same register, in which case this is not the same as + /// checking that an IR value has one use. bool hasTrivialKill(const Value *V); /// Create a machine mem operand from the given instruction. diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp index 62f7f3d98ba6d..0ff77d4ba1abb 100644 --- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp @@ -261,12 +261,16 @@ bool FastISel::hasTrivialKill(const Value *V) { if (GEP->hasAllZeroIndices() && !hasTrivialKill(GEP->getOperand(0))) return false; + // Casts and extractvalues may be trivially coalesced by fast-isel. + if (I->getOpcode() == Instruction::BitCast || + I->getOpcode() == Instruction::PtrToInt || + I->getOpcode() == Instruction::IntToPtr || + I->getOpcode() == Instruction::ExtractValue) + return false; + // Only instructions with a single use in the same basic block are considered // to have trivial kills. return I->hasOneUse() && - !(I->getOpcode() == Instruction::BitCast || - I->getOpcode() == Instruction::PtrToInt || - I->getOpcode() == Instruction::IntToPtr) && cast(*I->user_begin())->getParent() == I->getParent(); } diff --git a/llvm/test/CodeGen/X86/pr49467.ll b/llvm/test/CodeGen/X86/pr49467.ll new file mode 100644 index 0000000000000..9b35025520666 --- /dev/null +++ b/llvm/test/CodeGen/X86/pr49467.ll @@ -0,0 +1,27 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py +; RUN: llc -O0 -fast-isel -verify-machineinstrs -mtriple=x86_64 < %s | FileCheck %s + +declare { i8*, i64 } @get() + +declare void @use(i8*, i64) + +define void @test(i64* %p) nounwind { +; CHECK-LABEL: test: +; CHECK: # %bb.0: +; CHECK-NEXT: pushq %rax +; CHECK-NEXT: movq %rdi, (%rsp) # 8-byte Spill +; CHECK-NEXT: callq get@PLT +; CHECK-NEXT: movq (%rsp), %rdi # 8-byte Reload +; CHECK-NEXT: movq %rdx, %rsi +; CHECK-NEXT: movq %rsi, (%rdi) +; CHECK-NEXT: # implicit-def: $rdi +; CHECK-NEXT: callq use@PLT +; CHECK-NEXT: popq %rax +; CHECK-NEXT: retq + %struct = call { i8*, i64 } @get() + %struct.1 = extractvalue { i8*, i64 } %struct, 1 + store i64 %struct.1, i64* %p, align 8 + %struct.2 = extractvalue { i8*, i64 } %struct, 1 + call void @use(i8* undef, i64 %struct.2) + ret void +}