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[EarlyCSE] De-Duplicate callsites with differing attrs

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We only do this if the attributes of the two callsites are compatible
(intersectable) which is probably not in fact necessary.

Closes #110929
This commit is contained in:
Noah Goldstein 2024-10-02 15:53:17 -05:00
parent b9330e548e
commit b98c405f95
2 changed files with 33 additions and 22 deletions
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22
llvm/lib/Transforms/Scalar/EarlyCSE.cpp
View File

@ -362,7 +362,7 @@ static bool isEqualImpl(SimpleValue LHS, SimpleValue RHS) {
if (LHSI->getOpcode() != RHSI->getOpcode())
return false;
if (LHSI->isIdenticalToWhenDefined(RHSI)) {
if (LHSI->isIdenticalToWhenDefined(RHSI, /*IntersectAttrs=*/true)) {
// Convergent calls implicitly depend on the set of threads that is
// currently executing, so conservatively return false if they are in
// different basic blocks.
@ -551,7 +551,7 @@ bool DenseMapInfo<CallValue>::isEqual(CallValue LHS, CallValue RHS) {
if (LHSI->isConvergent() && LHSI->getParent() != RHSI->getParent())
return false;
return LHSI->isIdenticalTo(RHSI);
return LHSI->isIdenticalToWhenDefined(RHSI, /*IntersectAttrs=*/true);
}
//===----------------------------------------------------------------------===//
@ -1307,6 +1307,23 @@ static void combineIRFlags(Instruction &From, Value *To) {
(I->hasPoisonGeneratingFlags() && !programUndefinedIfPoison(I)))
I->andIRFlags(&From);
}
if (isa<CallBase>(&From) && isa<CallBase>(To)) {
// NB: Intersection of attrs between InVal.first and Inst is overly
// conservative. Since we only CSE readonly functions that have the same
// memory state, we can preserve (or possibly in some cases combine)
// more attributes. Likewise this implies when checking equality of
// callsite for CSEing, we can probably ignore more attributes.
// Generally poison generating attributes need to be handled with more
// care as they can create *new* UB if preserved/combined and violated.
// Attributes that imply immediate UB on the other hand would have been
// violated either way.
bool Success =
cast<CallBase>(To)->tryIntersectAttributes(cast<CallBase>(&From));
assert(Success && "Failed to intersect attributes in callsites that "
"passed identical check");
// For NDEBUG Compile.
(void)Success;
}
}
bool EarlyCSE::overridingStores(const ParseMemoryInst &Earlier,
@ -1632,6 +1649,7 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
LLVM_DEBUG(dbgs() << "Skipping due to debug counter\n");
continue;
}
combineIRFlags(Inst, InVal.first);
if (!Inst.use_empty())
Inst.replaceAllUsesWith(InVal.first);
salvageKnowledge(&Inst, &AC);

33
llvm/test/Transforms/EarlyCSE/replace-calls-def-attrs.ll
View File

@ -13,9 +13,8 @@ declare i8 @buz.fp(float, float)
define i8 @same_parent_combine_diff_attrs(i8 %x, i8 %y) {
; CHECK-LABEL: define i8 @same_parent_combine_diff_attrs(
; CHECK-SAME: i8 [[X:%.*]], i8 [[Y:%.*]]) {
; CHECK-NEXT: [[C2:%.*]] = call i8 @baz(i8 noundef [[X]], i8 noundef [[Y]]) #[[ATTR0:[0-9]+]]
; CHECK-NEXT: [[C1:%.*]] = call i8 @baz(i8 [[X]], i8 noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz(i8 [[C1]], i8 [[C2]])
; CHECK-NEXT: [[C1:%.*]] = call i8 @baz(i8 [[X]], i8 noundef [[Y]]) #[[ATTR0:[0-9]+]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz(i8 [[C1]], i8 [[C1]])
; CHECK-NEXT: ret i8 [[R]]
;
%c1 = call i8 @baz(i8 noundef %x, i8 noundef %y) readnone
@ -28,9 +27,8 @@ define i8 @same_parent_combine_diff_attrs(i8 %x, i8 %y) {
define i8 @same_parent_combine_diff_attrs_needs_intersect(i8 %x, i8 %y) {
; CHECK-LABEL: define i8 @same_parent_combine_diff_attrs_needs_intersect(
; CHECK-SAME: i8 [[X:%.*]], i8 [[Y:%.*]]) {
; CHECK-NEXT: [[C1:%.*]] = call nonnull ptr @baz.ptr(i8 noundef [[X]], i8 noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[C0:%.*]] = call ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C0]], ptr [[C1]])
; CHECK-NEXT: [[C1:%.*]] = call ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C1]], ptr [[C1]])
; CHECK-NEXT: ret i8 [[R]]
;
%c1 = call nonnull ptr @baz.ptr(i8 noundef %x, i8 noundef %y) readnone
@ -43,9 +41,8 @@ define i8 @same_parent_combine_diff_attrs_needs_intersect(i8 %x, i8 %y) {
define i8 @same_parent_combine_diff_attrs_fmf(float %x, float %y) {
; CHECK-LABEL: define i8 @same_parent_combine_diff_attrs_fmf(
; CHECK-SAME: float [[X:%.*]], float [[Y:%.*]]) {
; CHECK-NEXT: [[C1:%.*]] = call nnan nsz float @baz.fp(float noundef [[X]], float noundef [[Y]]) #[[ATTR1:[0-9]+]]
; CHECK-NEXT: [[C0:%.*]] = call nnan float @baz.fp(float [[X]], float noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.fp(float [[C0]], float [[C1]])
; CHECK-NEXT: [[C1:%.*]] = call nnan float @baz.fp(float [[X]], float noundef [[Y]]) #[[ATTR1:[0-9]+]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.fp(float [[C1]], float [[C1]])
; CHECK-NEXT: ret i8 [[R]]
;
%c1 = call nnan nsz float @baz.fp(float noundef %x, float noundef %y) readonly
@ -58,9 +55,8 @@ define i8 @same_parent_combine_diff_attrs_fmf(float %x, float %y) {
define i8 @same_parent_combine_diff_attrs_fmf2(float %x, float %y) {
; CHECK-LABEL: define i8 @same_parent_combine_diff_attrs_fmf2(
; CHECK-SAME: float [[X:%.*]], float [[Y:%.*]]) {
; CHECK-NEXT: [[C1:%.*]] = call nnan float @baz.fp(float noundef [[X]], float noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[C0:%.*]] = call nnan nsz float @baz.fp(float [[X]], float noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.fp(float [[C0]], float [[C1]])
; CHECK-NEXT: [[C1:%.*]] = call nnan float @baz.fp(float [[X]], float noundef [[Y]]) #[[ATTR0]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.fp(float [[C1]], float [[C1]])
; CHECK-NEXT: ret i8 [[R]]
;
%c1 = call nnan float @baz.fp(float noundef %x, float noundef %y) readnone
@ -73,9 +69,8 @@ define i8 @same_parent_combine_diff_attrs_fmf2(float %x, float %y) {
define i8 @same_parent_combine_diff_attrs_needs_intersect2(i8 %x, i8 %y) {
; CHECK-LABEL: define i8 @same_parent_combine_diff_attrs_needs_intersect2(
; CHECK-SAME: i8 [[X:%.*]], i8 [[Y:%.*]]) {
; CHECK-NEXT: [[C1:%.*]] = call nonnull ptr @baz.ptr(i8 noundef [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[C0:%.*]] = call ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C0]], ptr [[C1]])
; CHECK-NEXT: [[C1:%.*]] = call ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C1]], ptr [[C1]])
; CHECK-NEXT: ret i8 [[R]]
;
%c1 = call nonnull ptr @baz.ptr(i8 noundef %x, i8 noundef %y) readonly
@ -88,9 +83,8 @@ define i8 @same_parent_combine_diff_attrs_needs_intersect2(i8 %x, i8 %y) {
define i8 @same_parent_combine_diff_attrs_really_needs_intersect(i8 %x, i8 %y) {
; CHECK-LABEL: define i8 @same_parent_combine_diff_attrs_really_needs_intersect(
; CHECK-SAME: i8 [[X:%.*]], i8 [[Y:%.*]]) {
; CHECK-NEXT: [[C1:%.*]] = call nonnull ptr @baz.ptr(i8 noundef [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[C0:%.*]] = call ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C0]], ptr noundef [[C1]])
; CHECK-NEXT: [[C1:%.*]] = call ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C1]], ptr noundef [[C1]])
; CHECK-NEXT: ret i8 [[R]]
;
%c1 = call nonnull ptr @baz.ptr(i8 noundef %x, i8 noundef %y) readonly
@ -160,8 +154,7 @@ define i8 @diff_parent_combine_diff_attrs_preserves_return_attrs(i1 %c, i8 %x, i
; CHECK-NEXT: [[C1:%.*]] = call nonnull ptr @baz.ptr(i8 [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: br i1 [[C]], label %[[T:.*]], label %[[F:.*]]
; CHECK: [[T]]:
; CHECK-NEXT: [[C0:%.*]] = call nonnull ptr @baz.ptr(i8 noundef [[X]], i8 noundef [[Y]]) #[[ATTR1]]
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C0]], ptr noundef [[C1]])
; CHECK-NEXT: [[R:%.*]] = call i8 @buz.ptr(ptr [[C1]], ptr noundef [[C1]])
; CHECK-NEXT: ret i8 [[R]]
; CHECK: [[F]]:
; CHECK-NEXT: ret i8 9