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[DAGCombiner] Fix DAG combine store elimination, different address space. 

Fixes a bug in the DAG combiner that eliminates the stores because it missed
to inspect the address space of the pointers.

%v = load %ptr_as1
// no chain side effect
store %v, %ptr_as2

As well as

store %v, %ptr_as1
store %v, %ptr_as2

Fixes a test for above in X86.

Differential Revision: https://reviews.llvm.org/D102096
This commit is contained in:
Hendrik Greving 2021-05-11 08:57:18 -07:00
parent 4b00ffa767
commit 762ac725bf
2 changed files with 8 additions and 4 deletions
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7
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -17916,6 +17916,7 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Value)) {
if (Ld->getBasePtr() == Ptr && ST->getMemoryVT() == Ld->getMemoryVT() &&
ST->isUnindexed() && ST->isSimple() &&
Ld->getAddressSpace() == ST->getAddressSpace() &&
// There can't be any side effects between the load and store, such as
// a call or store.
Chain.reachesChainWithoutSideEffects(SDValue(Ld, 1))) {
@ -17929,7 +17930,8 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
if (ST->isUnindexed() && ST->isSimple() &&
ST1->isUnindexed() && ST1->isSimple()) {
if (ST1->getBasePtr() == Ptr && ST1->getValue() == Value &&
ST->getMemoryVT() == ST1->getMemoryVT()) {
ST->getMemoryVT() == ST1->getMemoryVT() &&
ST->getAddressSpace() == ST1->getAddressSpace()) {
// If this is a store followed by a store with the same value to the
// same location, then the store is dead/noop.
return Chain;
@ -17940,7 +17942,8 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
// BaseIndexOffset and the code below requires knowing the size
// of a vector, so bail out if MemoryVT is scalable.
!ST->getMemoryVT().isScalableVector() &&
!ST1->getMemoryVT().isScalableVector()) {
!ST1->getMemoryVT().isScalableVector() &&
ST->getAddressSpace() == ST1->getAddressSpace()) {
const BaseIndexOffset STBase = BaseIndexOffset::match(ST, DAG);
const BaseIndexOffset ChainBase = BaseIndexOffset::match(ST1, DAG);
unsigned STBitSize = ST->getMemoryVT().getFixedSizeInBits();

5
llvm/test/CodeGen/X86/dagcombine-dead-store.ll
View File

@ -6,12 +6,11 @@
; The test's 'same' and 'diff' notation depicts whether the pointer value is the same
; or different.
; FIXME: DAG combine incorrectly eliminates store if pointer is of same value.
define i32 @copy_fs_same() {
; CHECK-LABEL: copy_fs_same:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movl 1, %eax
; CHECK-NEXT: movl %eax, %fs:1
; CHECK-NEXT: retl
entry:
%0 = load i32, i32* inttoptr (i64 1 to i32*), align 4
@ -36,6 +35,7 @@ define void @output_fs_same(i32 %v) {
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
; CHECK-NEXT: movl %eax, 1
; CHECK-NEXT: movl %eax, %fs:1
; CHECK-NEXT: retl
entry:
store i32 %v, i32* inttoptr (i64 1 to i32*), align 4
@ -62,6 +62,7 @@ define void @output_indexed_fs_same(i32 %v, i32* %b) {
; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
; CHECK-NEXT: movl {{[0-9]+}}(%esp), %ecx
; CHECK-NEXT: movl %eax, 168(%ecx)
; CHECK-NEXT: movl %eax, %fs:168(%ecx)
; CHECK-NEXT: retl
%p = getelementptr i32, i32* %b, i64 42
%pa = addrspacecast i32* %p to i32 addrspace(257)*