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[SystemZ::TTI] Improve cost for compare of i64 with extended i32 load

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CGF/CLGF compares an i64 register with a sign/zero extended loaded i32 value
in memory.

This patch makes such a load considered foldable and so gets a 0 cost.

Review: Ulrich Weigand
https://reviews.llvm.org/D54944

llvm-svn: 347735
This commit is contained in:
Jonas Paulsson 2018-11-28 08:58:27 +00:00
parent 4328cc486d
commit ea9fed10ed
2 changed files with 26 additions and 8 deletions
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16
lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
View File

@ -915,16 +915,19 @@ isFoldableLoad(const LoadInst *Ld, const Instruction *&FoldedValue) {
switch (UserI->getOpcode()) {
case Instruction::Add: // SE: 16->32, 16/32->64, z14:16->64. ZE: 32->64
case Instruction::Sub:
case Instruction::ICmp:
if (LoadedBits == 32 && ZExtBits == 64)
return true;
LLVM_FALLTHROUGH;
case Instruction::Mul: // SE: 16->32, 32->64, z14:16->64
if (LoadedBits == 16 &&
(SExtBits == 32 ||
(SExtBits == 64 && ST->hasMiscellaneousExtensions2())))
return true;
if (LoadOrTruncBits == 16)
return true;
if (UserI->getOpcode() != Instruction::ICmp) {
if (LoadedBits == 16 &&
(SExtBits == 32 ||
(SExtBits == 64 && ST->hasMiscellaneousExtensions2())))
return true;
if (LoadOrTruncBits == 16)
return true;
}
LLVM_FALLTHROUGH;
case Instruction::SDiv:// SE: 32->64
if (LoadedBits == 32 && SExtBits == 64)
@ -934,7 +937,6 @@ isFoldableLoad(const LoadInst *Ld, const Instruction *&FoldedValue) {
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
case Instruction::ICmp:
// This also makes sense for float operations, but disabled for now due
// to regressions.
// case Instruction::FCmp:

18
test/Analysis/CostModel/SystemZ/memop-folding-int-arith.ll
View File

@ -726,6 +726,16 @@ define void @icmp() {
%tr_0 = trunc i64 %li64_2 to i32
icmp eq i32 %tr_0, undef
; Sign-extended load
%li32_2 = load i32, i32* undef
%sext = sext i32 %li32_2 to i64
icmp eq i64 %sext, undef
; Zero-extended load
%li32_3 = load i32, i32* undef
%zext = zext i32 %li32_3 to i64
icmp eq i64 %zext, undef
; Loads with multiple uses are *not* folded
%li64_3 = load i64, i64* undef
%tr_1 = trunc i64 %li64_3 to i32
@ -745,7 +755,13 @@ define void @icmp() {
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %li64_2 = load i64, i64* undef
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %tr_0 = trunc i64 %li64_2 to i32
; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %5 = icmp eq i32 %tr_0, undef
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %li32_2 = load i32, i32* undef
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %sext = sext i32 %li32_2 to i64
; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %6 = icmp eq i64 %sext, undef
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %li32_3 = load i32, i32* undef
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %zext = zext i32 %li32_3 to i64
; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %7 = icmp eq i64 %zext, undef
; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %li64_3 = load i64, i64* undef
; CHECK: Cost Model: Found an estimated cost of 0 for instruction: %tr_1 = trunc i64 %li64_3 to i32
; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %6 = icmp eq i64 %li64_3, undef
; CHECK: Cost Model: Found an estimated cost of 1 for instruction: %8 = icmp eq i64 %li64_3, undef
}