Author: jonpa
Date: Wed Nov 28 00:08:05 2018
New Revision: 347733
URL: http://llvm.org/viewvc/llvm-project?rev=347733&view=rev
Log:
[SystemZ::TTI] Improved cost values for comparison against memory.
Single instructions exist for i8 and i16 comparisons of memory against a
small immediate.
This patch makes sure that if the load in these cases has a single user (the
ICmp), it gets a 0 cost (folded), and also that the ICmp gets a cost of 1.
Review: Ulrich Weigand
https://reviews.llvm.org/D54897
Added:
llvm/trunk/test/Analysis/CostModel/SystemZ/cmp-mem.ll
Modified:
llvm/trunk/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
Modified: llvm/trunk/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp?rev=347733&r1=347732&r2=347733&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp Wed Nov 28 00:08:05 2018
@@ -835,8 +835,17 @@ int SystemZTTIImpl::getCmpSelInstrCost(u
switch (Opcode) {
case Instruction::ICmp: {
unsigned Cost = 1;
- if (ValTy->isIntegerTy() && ValTy->getScalarSizeInBits() <= 16)
+ if (ValTy->isIntegerTy() && ValTy->getScalarSizeInBits() <= 16) {
+ if (I != nullptr) {
+ // Single instruction for comparison of memory with a small immediate.
+ if (const LoadInst* Ld = dyn_cast<LoadInst>(I->getOperand(0))) {
+ const Instruction *FoldedValue = nullptr;
+ if (isFoldableLoad(Ld, FoldedValue))
+ return Cost;
+ }
+ }
Cost += 2; // extend both operands
+ }
return Cost;
}
case Instruction::Select:
@@ -932,6 +941,12 @@ isFoldableLoad(const LoadInst *Ld, const
if (SExtBits || ZExtBits)
return false;
+ // Comparison between memory and immediate.
+ if (UserI->getOpcode() == Instruction::ICmp)
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(UserI->getOperand(1)))
+ if (isUInt<16>(CI->getZExtValue()))
+ return true;
+
unsigned LoadOrTruncBits = (TruncBits ? TruncBits : LoadedBits);
return (LoadOrTruncBits == 32 || LoadOrTruncBits == 64);
break;
Added: llvm/trunk/test/Analysis/CostModel/SystemZ/cmp-mem.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/CostModel/SystemZ/cmp-mem.ll?rev=347733&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/CostModel/SystemZ/cmp-mem.ll (added)
+++ llvm/trunk/test/Analysis/CostModel/SystemZ/cmp-mem.ll Wed Nov 28 00:08:05 2018
@@ -0,0 +1,27 @@
+; RUN: opt < %s -cost-model -analyze -mtriple=systemz-unknown -mcpu=z13 | FileCheck %s
+;
+; Test costs for i8 and i16 comparisons against memory with a small immediate.
+
+define i32 @fun0(i8* %Src, i8* %Dst, i8 %Val) {
+; CHECK: Printing analysis 'Cost Model Analysis' for function 'fun0':
+; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %Ld = load i8, i8* %Src
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %Cmp = icmp eq i8 %Ld, 123
+; CHECK: Cost Model: Found an estimated cost of 2 for instruction: %Ret = zext i1 %Cmp to i32
+; CHECK: Cost Model: Found an estimated cost of 0 for instruction: ret i32 %Ret
+ %Ld = load i8, i8* %Src
+ %Cmp = icmp eq i8 %Ld, 123
+ %Ret = zext i1 %Cmp to i32
+ ret i32 %Ret
+}
+
+define i32 @fun1(i16* %Src, i16* %Dst, i16 %Val) {
+; CHECK: Printing analysis 'Cost Model Analysis' for function 'fun1':
+; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %Ld = load i16, i16* %Src
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %Cmp = icmp eq i16
+; CHECK: Cost Model: Found an estimated cost of 2 for instruction: %Ret = zext i1 %Cmp to i32
+; CHECK: Cost Model: Found an estimated cost of 0 for instruction: ret i32 %Ret
+ %Ld = load i16, i16* %Src
+ %Cmp = icmp eq i16 %Ld, 1234
+ %Ret = zext i1 %Cmp to i32
+ ret i32 %Ret
+}