From 6e17aa45a392fa998fe9316267dfd9eb82eeea99 Mon Sep 17 00:00:00 2001 From: Juergen Ributzka Date: Sat, 12 Apr 2014 02:36:28 +0000 Subject: [PATCH] [ARM64] Fix the cost model for cheap large constants. Originally the cost model would give up for large constants and just return the maximum cost. This is not what we want for constant hoisting, because some of these constants are large in bitwidth, but are still cheap to materialize. This commit fixes the cost model to either return TCC_Free if the cost cannot be determined, or accurately calculate the cost even for large constants (bitwidth > 128). This fixes . llvm-svn: 206100 --- llvm/lib/Target/ARM64/ARM64TargetTransformInfo.cpp | 14 +++++++++----- .../ConstantHoisting/ARM64/large-immediate.ll | 8 ++++++++ 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/llvm/lib/Target/ARM64/ARM64TargetTransformInfo.cpp b/llvm/lib/Target/ARM64/ARM64TargetTransformInfo.cpp index f12d1be81a16..cc8cc806ec70 100644 --- a/llvm/lib/Target/ARM64/ARM64TargetTransformInfo.cpp +++ b/llvm/lib/Target/ARM64/ARM64TargetTransformInfo.cpp @@ -154,7 +154,7 @@ unsigned ARM64TTI::getIntImmCost(const APInt &Imm, Type *Ty) const { assert(Ty->isIntegerTy()); unsigned BitSize = Ty->getPrimitiveSizeInBits(); - if (BitSize == 0 || BitSize > 128) + if (BitSize == 0) return ~0U; // Sign-extend all constants to a multiple of 64-bit. @@ -179,8 +179,10 @@ unsigned ARM64TTI::getIntImmCost(unsigned Opcode, unsigned Idx, assert(Ty->isIntegerTy()); unsigned BitSize = Ty->getPrimitiveSizeInBits(); - if (BitSize == 0 || BitSize > 128) - return ~0U; + // There is no cost model for constants with a bit size of 0. Return TCC_Free + // here, so that constant hoisting will ignore this constant. + if (BitSize == 0) + return TCC_Free; unsigned ImmIdx = ~0U; switch (Opcode) { @@ -238,8 +240,10 @@ unsigned ARM64TTI::getIntImmCost(Intrinsic::ID IID, unsigned Idx, assert(Ty->isIntegerTy()); unsigned BitSize = Ty->getPrimitiveSizeInBits(); - if (BitSize == 0 || BitSize > 128) - return ~0U; + // There is no cost model for constants with a bit size of 0. Return TCC_Free + // here, so that constant hoisting will ignore this constant. + if (BitSize == 0) + return TCC_Free; switch (IID) { default: diff --git a/llvm/test/Transforms/ConstantHoisting/ARM64/large-immediate.ll b/llvm/test/Transforms/ConstantHoisting/ARM64/large-immediate.ll index 0965a45ea6ed..92ad6ee70de7 100644 --- a/llvm/test/Transforms/ConstantHoisting/ARM64/large-immediate.ll +++ b/llvm/test/Transforms/ConstantHoisting/ARM64/large-immediate.ll @@ -8,3 +8,11 @@ define i128 @test1(i128 %a) nounwind { ret i128 %2 } +; Check that we don't hoist large, but cheap constants +define i512 @test2(i512 %a) nounwind { +; CHECK-LABEL: test2 +; CHECK-NOT: %const = bitcast i512 7 to i512 + %1 = and i512 %a, 7 + %2 = or i512 %1, 7 + ret i512 %2 +}