[llvm] fcf2d5f - Revert "SROA: Enhance speculateSelectInstLoads"
Christudasan Devadasan via llvm-commits
llvm-commits at lists.llvm.org
Sun Aug 8 22:25:35 PDT 2021
Author: Christudasan Devadasan
Date: 2021-08-09T01:13:39-04:00
New Revision: fcf2d5f40296be4e0f0e954001beb7814f97a212
URL: https://github.com/llvm/llvm-project/commit/fcf2d5f40296be4e0f0e954001beb7814f97a212
DIFF: https://github.com/llvm/llvm-project/commit/fcf2d5f40296be4e0f0e954001beb7814f97a212.diff
LOG: Revert "SROA: Enhance speculateSelectInstLoads"
This reverts commit ffc3fb665d0a0dccd64cc8c803ad8cc1a0d5dfa1.
Added:
Modified:
llvm/lib/Transforms/Scalar/SROA.cpp
llvm/test/Transforms/SROA/phi-and-select.ll
Removed:
llvm/test/Transforms/SROA/select-load.ll
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 4a6bf97602e52..b3c4308ae80cc 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1330,21 +1330,14 @@ static void speculatePHINodeLoads(PHINode &PN) {
/// %V = select i1 %cond, i32 %V1, i32 %V2
///
/// We can do this to a select if its only uses are loads and if the operand
-/// to the select can be loaded unconditionally. If found an intervening bitcast
-/// with a single use of the load, allow the promotion.
+/// to the select can be loaded unconditionally.
static bool isSafeSelectToSpeculate(SelectInst &SI) {
Value *TValue = SI.getTrueValue();
Value *FValue = SI.getFalseValue();
const DataLayout &DL = SI.getModule()->getDataLayout();
for (User *U : SI.users()) {
- LoadInst *LI;
- BitCastInst *BC = dyn_cast<BitCastInst>(U);
- if (BC && BC->hasOneUse())
- LI = dyn_cast<LoadInst>(*BC->user_begin());
- else
- LI = dyn_cast<LoadInst>(U);
-
+ LoadInst *LI = dyn_cast<LoadInst>(U);
if (!LI || !LI->isSimple())
return false;
@@ -1370,24 +1363,10 @@ static void speculateSelectInstLoads(SelectInst &SI) {
Value *FV = SI.getFalseValue();
// Replace the loads of the select with a select of two loads.
while (!SI.use_empty()) {
- LoadInst *LI;
- BitCastInst *BC = dyn_cast<BitCastInst>(SI.user_back());
- if (BC) {
- assert(BC->hasOneUse() && "Bitcast should have a single use.");
- LI = cast<LoadInst>(BC->user_back());
- } else {
- LI = cast<LoadInst>(SI.user_back());
- }
-
+ LoadInst *LI = cast<LoadInst>(SI.user_back());
assert(LI->isSimple() && "We only speculate simple loads");
IRB.SetInsertPoint(LI);
- if (BC) {
- // Cast the operands to bitcast's target type.
- TV = IRB.CreateBitCast(TV, BC->getType(), TV->getName() + ".sroa.cast");
- FV = IRB.CreateBitCast(FV, BC->getType(), FV->getName() + ".sroa.cast");
- }
-
LoadInst *TL = IRB.CreateLoad(LI->getType(), TV,
LI->getName() + ".sroa.speculate.load.true");
LoadInst *FL = IRB.CreateLoad(LI->getType(), FV,
@@ -1411,8 +1390,6 @@ static void speculateSelectInstLoads(SelectInst &SI) {
LLVM_DEBUG(dbgs() << " speculated to: " << *V << "\n");
LI->replaceAllUsesWith(V);
LI->eraseFromParent();
- if (BC)
- BC->eraseFromParent();
}
SI.eraseFromParent();
}
diff --git a/llvm/test/Transforms/SROA/phi-and-select.ll b/llvm/test/Transforms/SROA/phi-and-select.ll
index d1863359b1630..c773714981359 100644
--- a/llvm/test/Transforms/SROA/phi-and-select.ll
+++ b/llvm/test/Transforms/SROA/phi-and-select.ll
@@ -60,14 +60,23 @@ entry:
ret i32 %result
}
+; If bitcast isn't considered a safe phi/select use, the alloca
+; remains as an array.
+; FIXME: Why isn't this identical to test2?
define float @test2_bitcast() {
; CHECK-LABEL: @test2_bitcast(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[COND:%.*]] = icmp sle i32 0, 1
-; CHECK-NEXT: [[TMP0:%.*]] = bitcast i32 1 to float
-; CHECK-NEXT: [[TMP1:%.*]] = bitcast i32 0 to float
-; CHECK-NEXT: [[RESULT_SROA_SPECULATED:%.*]] = select i1 [[COND]], float [[TMP0]], float [[TMP1]]
-; CHECK-NEXT: ret float [[RESULT_SROA_SPECULATED]]
+; CHECK-NEXT: [[A_SROA_0:%.*]] = alloca i32, align 4
+; CHECK-NEXT: [[A_SROA_3:%.*]] = alloca i32, align 4
+; CHECK-NEXT: store i32 0, i32* [[A_SROA_0]], align 4
+; CHECK-NEXT: store i32 1, i32* [[A_SROA_3]], align 4
+; CHECK-NEXT: [[A_SROA_0_0_A_SROA_0_0_V0:%.*]] = load i32, i32* [[A_SROA_0]], align 4
+; CHECK-NEXT: [[A_SROA_3_0_A_SROA_3_4_V1:%.*]] = load i32, i32* [[A_SROA_3]], align 4
+; CHECK-NEXT: [[COND:%.*]] = icmp sle i32 [[A_SROA_0_0_A_SROA_0_0_V0]], [[A_SROA_3_0_A_SROA_3_4_V1]]
+; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[COND]], i32* [[A_SROA_3]], i32* [[A_SROA_0]]
+; CHECK-NEXT: [[SELECT_BC:%.*]] = bitcast i32* [[SELECT]] to float*
+; CHECK-NEXT: [[RESULT:%.*]] = load float, float* [[SELECT_BC]], align 4
+; CHECK-NEXT: ret float [[RESULT]]
;
entry:
%a = alloca [2 x i32]
diff --git a/llvm/test/Transforms/SROA/select-load.ll b/llvm/test/Transforms/SROA/select-load.ll
deleted file mode 100644
index 60cbae4fb1e59..0000000000000
--- a/llvm/test/Transforms/SROA/select-load.ll
+++ /dev/null
@@ -1,35 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -sroa < %s | FileCheck %s
-
-%st.half = type { half }
-
-; Allow speculateSelectInstLoads to fold load and select
-; even if there is an intervening bitcast.
-define <2 x i16> @test_load_bitcast_select(i1 %cond1, i1 %cond2) {
-; CHECK-LABEL: @test_load_bitcast_select(
-; CHECK-NEXT: [[TMP1:%.*]] = bitcast half 0xHFFFF to i16
-; CHECK-NEXT: [[TMP2:%.*]] = bitcast half 0xH0000 to i16
-; CHECK-NEXT: [[LD1_SROA_SPECULATED:%.*]] = select i1 [[COND1:%.*]], i16 [[TMP1]], i16 [[TMP2]]
-; CHECK-NEXT: [[V1:%.*]] = insertelement <2 x i16> undef, i16 [[LD1_SROA_SPECULATED]], i32 0
-; CHECK-NEXT: [[TMP3:%.*]] = bitcast half 0xHFFFF to i16
-; CHECK-NEXT: [[TMP4:%.*]] = bitcast half 0xH0000 to i16
-; CHECK-NEXT: [[LD2_SROA_SPECULATED:%.*]] = select i1 [[COND2:%.*]], i16 [[TMP3]], i16 [[TMP4]]
-; CHECK-NEXT: [[V2:%.*]] = insertelement <2 x i16> [[V1]], i16 [[LD2_SROA_SPECULATED]], i32 1
-; CHECK-NEXT: ret <2 x i16> [[V2]]
-;
- %true = alloca half, align 2
- %false = alloca half, align 2
- store half 0xHFFFF, half* %true, align 2
- store half 0xH0000, half* %false, align 2
- %false.cast = bitcast half* %false to %st.half*
- %true.cast = bitcast half* %true to %st.half*
- %sel1 = select i1 %cond1, %st.half* %true.cast, %st.half* %false.cast
- %cast1 = bitcast %st.half* %sel1 to i16*
- %ld1 = load i16, i16* %cast1, align 2
- %v1 = insertelement <2 x i16> undef, i16 %ld1, i32 0
- %sel2 = select i1 %cond2, %st.half* %true.cast, %st.half* %false.cast
- %cast2 = bitcast %st.half* %sel2 to i16*
- %ld2 = load i16, i16* %cast2, align 2
- %v2 = insertelement <2 x i16> %v1, i16 %ld2, i32 1
- ret <2 x i16> %v2
-}
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