[llvm] e2c2124 - Reapply [InstCombine] Extract bitcast -> gep transform
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 21 13:03:28 PDT 2021
Author: Nikita Popov
Date: 2021-06-21T22:03:15+02:00
New Revision: e2c2124a4b5bad9cf2a1e23a6aef1b2ad753f504
URL: https://github.com/llvm/llvm-project/commit/e2c2124a4b5bad9cf2a1e23a6aef1b2ad753f504
DIFF: https://github.com/llvm/llvm-project/commit/e2c2124a4b5bad9cf2a1e23a6aef1b2ad753f504.diff
LOG: Reapply [InstCombine] Extract bitcast -> gep transform
Relative to the original patch, an InstCombine test has been
added to show a previously missed pattern, and the Coroutine
test that resulted in the revert has been regenerated.
-----
Move this into a separate function, to make sure that early
returns do not accidentally skip other transforms. This previously
happened for the isSized() check, which skipped folds like
distributing a bitcast over a select.
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
llvm/test/Transforms/InstCombine/bitcast.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 9b38eb6ab24df..dcfff4552f11e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2603,6 +2603,52 @@ Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
return RetVal;
}
+static Instruction *convertBitCastToGEP(BitCastInst &CI, IRBuilderBase &Builder,
+ const DataLayout &DL) {
+ Value *Src = CI.getOperand(0);
+ PointerType *SrcPTy = cast<PointerType>(Src->getType());
+ PointerType *DstPTy = cast<PointerType>(CI.getType());
+ Type *DstElTy = DstPTy->getElementType();
+ Type *SrcElTy = SrcPTy->getElementType();
+
+ // When the type pointed to is not sized the cast cannot be
+ // turned into a gep.
+ if (!SrcElTy->isSized())
+ return nullptr;
+
+ // If the source and destination are pointers, and this cast is equivalent
+ // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
+ // This can enhance SROA and other transforms that want type-safe pointers.
+ unsigned NumZeros = 0;
+ while (SrcElTy && SrcElTy != DstElTy) {
+ SrcElTy = GetElementPtrInst::getTypeAtIndex(SrcElTy, (uint64_t)0);
+ ++NumZeros;
+ }
+
+ // If we found a path from the src to dest, create the getelementptr now.
+ if (SrcElTy == DstElTy) {
+ SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
+ GetElementPtrInst *GEP =
+ GetElementPtrInst::Create(SrcPTy->getElementType(), Src, Idxs);
+
+ // If the source pointer is dereferenceable, then assume it points to an
+ // allocated object and apply "inbounds" to the GEP.
+ bool CanBeNull, CanBeFreed;
+ if (Src->getPointerDereferenceableBytes(DL, CanBeNull, CanBeFreed)) {
+ // In a non-default address space (not 0), a null pointer can not be
+ // assumed inbounds, so ignore that case (dereferenceable_or_null).
+ // The reason is that 'null' is not treated
diff erently in these address
+ // spaces, and we consequently ignore the 'gep inbounds' special case
+ // for 'null' which allows 'inbounds' on 'null' if the indices are
+ // zeros.
+ if (SrcPTy->getAddressSpace() == 0 || !CanBeNull)
+ GEP->setIsInBounds();
+ }
+ return GEP;
+ }
+ return nullptr;
+}
+
Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
// If the operands are integer typed then apply the integer transforms,
// otherwise just apply the common ones.
@@ -2616,11 +2662,6 @@ Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
return replaceInstUsesWith(CI, Src);
if (isa<PointerType>(SrcTy) && isa<PointerType>(DestTy)) {
- PointerType *SrcPTy = cast<PointerType>(SrcTy);
- PointerType *DstPTy = cast<PointerType>(DestTy);
- Type *DstElTy = DstPTy->getElementType();
- Type *SrcElTy = SrcPTy->getElementType();
-
// If we are casting a alloca to a pointer to a type of the same
// size, rewrite the allocation instruction to allocate the "right" type.
// There is no need to modify malloc calls because it is their bitcast that
@@ -2629,43 +2670,8 @@ Instruction *InstCombinerImpl::visitBitCast(BitCastInst &CI) {
if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
return V;
- // When the type pointed to is not sized the cast cannot be
- // turned into a gep.
- Type *PointeeType =
- cast<PointerType>(Src->getType()->getScalarType())->getElementType();
- if (!PointeeType->isSized())
- return nullptr;
-
- // If the source and destination are pointers, and this cast is equivalent
- // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
- // This can enhance SROA and other transforms that want type-safe pointers.
- unsigned NumZeros = 0;
- while (SrcElTy && SrcElTy != DstElTy) {
- SrcElTy = GetElementPtrInst::getTypeAtIndex(SrcElTy, (uint64_t)0);
- ++NumZeros;
- }
-
- // If we found a path from the src to dest, create the getelementptr now.
- if (SrcElTy == DstElTy) {
- SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0));
- GetElementPtrInst *GEP =
- GetElementPtrInst::Create(SrcPTy->getElementType(), Src, Idxs);
-
- // If the source pointer is dereferenceable, then assume it points to an
- // allocated object and apply "inbounds" to the GEP.
- bool CanBeNull, CanBeFreed;
- if (Src->getPointerDereferenceableBytes(DL, CanBeNull, CanBeFreed)) {
- // In a non-default address space (not 0), a null pointer can not be
- // assumed inbounds, so ignore that case (dereferenceable_or_null).
- // The reason is that 'null' is not treated
diff erently in these address
- // spaces, and we consequently ignore the 'gep inbounds' special case
- // for 'null' which allows 'inbounds' on 'null' if the indices are
- // zeros.
- if (SrcPTy->getAddressSpace() == 0 || !CanBeNull)
- GEP->setIsInBounds();
- }
- return GEP;
- }
+ if (Instruction *I = convertBitCastToGEP(CI, Builder, DL))
+ return I;
}
if (FixedVectorType *DestVTy = dyn_cast<FixedVectorType>(DestTy)) {
diff --git a/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll b/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
index d06564dab985a..ea524a6afcc22 100644
--- a/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
+++ b/llvm/test/Transforms/Coroutines/coro-retcon-once-value.ll
@@ -12,12 +12,11 @@ define {i8*, i32} @f(i8* %buffer, i32* %array) {
; CHECK-NEXT: store i32* [[ARRAY:%.*]], i32** [[ARRAY_SPILL_ADDR]], align 8
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[ARRAY]], align 4
; CHECK-NEXT: [[LOAD_POS:%.*]] = icmp sgt i32 [[LOAD]], 0
-; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[LOAD_POS]], void (i8*, i1)* @f.resume.0, void (i8*, i1)* @f.resume.1
-; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[LOAD_POS]], i32 [[LOAD]], i32 0
-; CHECK-NEXT: [[TMP2:%.*]] = bitcast void (i8*, i1)* [[TMP0]] to i8*
-; CHECK-NEXT: [[TMP3:%.*]] = insertvalue { i8*, i32 } undef, i8* [[TMP2]], 0
-; CHECK-NEXT: [[TMP4:%.*]] = insertvalue { i8*, i32 } [[TMP3]], i32 [[TMP1]], 1
-; CHECK-NEXT: ret { i8*, i32 } [[TMP4]]
+; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[LOAD_POS]], i32 [[LOAD]], i32 0
+; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[LOAD_POS]], i8* bitcast (void (i8*, i1)* @f.resume.0 to i8*), i8* bitcast (void (i8*, i1)* @f.resume.1 to i8*)
+; CHECK-NEXT: [[TMP2:%.*]] = insertvalue { i8*, i32 } undef, i8* [[TMP1]], 0
+; CHECK-NEXT: [[TMP3:%.*]] = insertvalue { i8*, i32 } [[TMP2]], i32 [[TMP0]], 1
+; CHECK-NEXT: ret { i8*, i32 } [[TMP3]]
;
entry:
%id = call token @llvm.coro.id.retcon.once(i32 8, i32 8, i8* %buffer, i8* bitcast (void (i8*, i1)* @prototype to i8*), i8* bitcast (i8* (i32)* @allocate to i8*), i8* bitcast (void (i8*)* @deallocate to i8*))
@@ -58,10 +57,10 @@ define void @test(i32* %array) {
; CHECK-NEXT: store i32* [[ARRAY:%.*]], i32** [[TMP0]], align 8
; CHECK-NEXT: [[LOAD_I:%.*]] = load i32, i32* [[ARRAY]], align 4
; CHECK-NEXT: [[LOAD_POS_I:%.*]] = icmp sgt i32 [[LOAD_I]], 0
-; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[LOAD_POS_I]], void (i8*, i1)* @f.resume.0, void (i8*, i1)* @f.resume.1
-; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[LOAD_POS_I]], i32 [[LOAD_I]], i32 0
-; CHECK-NEXT: call void @print(i32 [[TMP2]])
-; CHECK-NEXT: call void [[TMP1]](i8* nonnull [[DOTSUB]], i1 zeroext false)
+; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[LOAD_POS_I]], i32 [[LOAD_I]], i32 0
+; CHECK-NEXT: call void @print(i32 [[TMP1]])
+; CHECK-NEXT: [[CONT_CAST:%.*]] = select i1 [[LOAD_POS_I]], void (i8*, i1)* @f.resume.0, void (i8*, i1)* @f.resume.1
+; CHECK-NEXT: call void [[CONT_CAST]](i8* nonnull [[DOTSUB]], i1 zeroext false)
; CHECK-NEXT: ret void
;
entry:
diff --git a/llvm/test/Transforms/InstCombine/bitcast.ll b/llvm/test/Transforms/InstCombine/bitcast.ll
index 9c509d9691314..3699f7fa301c9 100644
--- a/llvm/test/Transforms/InstCombine/bitcast.ll
+++ b/llvm/test/Transforms/InstCombine/bitcast.ll
@@ -584,8 +584,7 @@ declare void @f1()
declare void @f2()
define i8* @select_bitcast_unsized_pointer(i1 %c) {
; CHECK-LABEL: @select_bitcast_unsized_pointer(
-; CHECK-NEXT: [[S:%.*]] = select i1 [[C:%.*]], void ()* @f1, void ()* @f2
-; CHECK-NEXT: [[B:%.*]] = bitcast void ()* [[S]] to i8*
+; CHECK-NEXT: [[B:%.*]] = select i1 [[C:%.*]], i8* bitcast (void ()* @f1 to i8*), i8* bitcast (void ()* @f2 to i8*)
; CHECK-NEXT: ret i8* [[B]]
;
%s = select i1 %c, void ()* @f1, void ()* @f2
More information about the llvm-commits
mailing list