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Revert "[GlobalOpt] Perform store->dominated load forwarding for stored once globals" 

This reverts commit 6f348b146b.

Am seeing internal test failures plus a linux kernel breakage reported due to this.
This commit is contained in:
Arthur Eubanks 2022-06-20 10:26:47 -07:00
parent 1cd2c72bef
commit 13ff7d6f39
8 changed files with 22 additions and 55 deletions
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35
llvm/lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -1438,37 +1438,6 @@ static void makeAllConstantUsesInstructions(Constant *C) {
}
}
// For a global variable with one store, if the store dominates any loads,
// those loads will always load the stored value (as opposed to the
// initializer), even in the presence of recursion.
static bool forwardStoredOnceStore(
GlobalVariable *GV, const StoreInst *StoredOnceStore,
function_ref<DominatorTree &(Function &)> LookupDomTree) {
const Value *StoredOnceValue = StoredOnceStore->getValueOperand();
SmallVector<LoadInst *> Loads;
const Function *F = StoredOnceStore->getFunction();
for (User *U : GV->users()) {
if (auto *LI = dyn_cast<LoadInst>(U)) {
if (LI->getFunction() == F &&
LI->getType() == StoredOnceValue->getType() && LI->isSimple())
Loads.push_back(LI);
}
}
// Only compute DT if we have any loads to examine.
bool MadeChange = false;
if (!Loads.empty()) {
auto &DT = LookupDomTree(*const_cast<Function *>(F));
for (auto *LI : Loads) {
if (DT.dominates(StoredOnceStore, LI)) {
LI->replaceAllUsesWith(const_cast<Value *>(StoredOnceValue));
LI->eraseFromParent();
MadeChange = true;
}
}
}
return MadeChange;
}
/// Analyze the specified global variable and optimize
/// it if possible. If we make a change, return true.
static bool
@ -1628,10 +1597,6 @@ processInternalGlobal(GlobalVariable *GV, const GlobalStatus &GS,
if (optimizeOnceStoredGlobal(GV, StoredOnceValue, DL, GetTLI))
return true;
// Try to forward the store to any loads.
if (forwardStoredOnceStore(GV, GS.StoredOnceStore, LookupDomTree))
return true;
// Otherwise, if the global was not a boolean, we can shrink it to be a
// boolean. Skip this optimization for AS that doesn't allow an initializer.
if (SOVConstant && GS.Ordering == AtomicOrdering::NotAtomic &&

3
llvm/test/Transforms/GlobalOpt/malloc-promote-1-no-null-opt.ll
View File

@ -12,7 +12,8 @@ define void @init() #0 {
; CHECK-NEXT: [[MALLOCCALL:%.*]] = tail call i8* @malloc(i64 4)
; CHECK-NEXT: [[P:%.*]] = bitcast i8* [[MALLOCCALL]] to i32*
; CHECK-NEXT: store i32* [[P]], i32** @G, align 8
; CHECK-NEXT: store i32 0, i32* [[P]], align 4
; CHECK-NEXT: [[GV:%.*]] = load i32*, i32** @G, align 8
; CHECK-NEXT: store i32 0, i32* [[GV]], align 4
; CHECK-NEXT: ret void
;
%malloccall = tail call i8* @malloc(i64 4)

3
llvm/test/Transforms/GlobalOpt/malloc-promote-2-no-null-opt.ll
View File

@ -12,7 +12,8 @@ define void @t() #0 {
; CHECK-NEXT: [[MALLOCCALL:%.*]] = tail call i8* @malloc(i64 400)
; CHECK-NEXT: [[P:%.*]] = bitcast i8* [[MALLOCCALL]] to i32*
; CHECK-NEXT: store i32* [[P]], i32** @G, align 8
; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[P]], i32 40
; CHECK-NEXT: [[GV:%.*]] = load i32*, i32** @G, align 8
; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[GV]], i32 40
; CHECK-NEXT: store i32 20, i32* [[GVE]], align 4
; CHECK-NEXT: ret void
;

3
llvm/test/Transforms/GlobalOpt/malloc-promote-3.ll
View File

@ -12,7 +12,8 @@ define void @t() {
; CHECK-NEXT: [[MALLOCCALL:%.*]] = tail call i8* @malloc(i64 400) #[[ATTR0:[0-9]+]]
; CHECK-NEXT: [[P:%.*]] = bitcast i8* [[MALLOCCALL]] to i32*
; CHECK-NEXT: store i32* [[P]], i32** @G, align 8
; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[P]], i32 40
; CHECK-NEXT: [[GV:%.*]] = load i32*, i32** @G, align 8
; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[GV]], i32 40
; CHECK-NEXT: store i32 20, i32* [[GVE]], align 4
; CHECK-NEXT: ret void
;

13
llvm/test/Transforms/GlobalOpt/shrink-global-to-bool-check-debug.ll
View File

@ -2,24 +2,21 @@
@foo = internal global i32 0, align 4
define void @store() {
define dso_local i32 @bar() {
entry:
store i32 5, i32* @foo, align 4
ret void
}
define i32 @bar() {
entry:
%0 = load i32, i32* @foo, align 4
ret i32 %0
}
;CHECK: @bar
;CHECK-NEXT: entry:
;CHECK-NEXT: store i1 true, i1* @foo, align 1, !dbg ![[DbgLocStore:[0-9]+]]
;CHECK-NEXT: %.b = load i1, i1* @foo, align 1, !dbg ![[DbgLocLoadSel:[0-9]+]]
;CHECK-NEXT: %0 = select i1 %.b, i32 5, i32 0, !dbg ![[DbgLocLoadSel]]
;CHECK-NEXT: call void @llvm.dbg.value({{.*}}), !dbg ![[DbgLocLoadSel]]
;CHECK-NEXT: ret i32 %0, !dbg ![[DbgLocRet:[0-9]+]]
;CHECK: ![[DbgLocLoadSel]] = !DILocation(line: 3,
;CHECK: ![[DbgLocRet]] = !DILocation(line: 4,
;CHECK: ![[DbgLocStore]] = !DILocation(line: 1,
;CHECK: ![[DbgLocLoadSel]] = !DILocation(line: 2,
;CHECK: ![[DbgLocRet]] = !DILocation(line: 3,

8
llvm/test/Transforms/GlobalOpt/shrink-global-to-bool.ll
View File

@ -10,13 +10,11 @@
; Negative test for AS(3). Skip shrink global to bool optimization.
; CHECK: @lvar = internal unnamed_addr addrspace(3) global i32 undef
define void @test_global_var(i1 %i) {
define void @test_global_var() {
; CHECK-LABEL: @test_global_var(
; CHECK: store volatile i32 10, i32* undef, align 4
;
entry:
br i1 %i, label %bb1, label %exit
bb1:
store i32 10, i32* @gvar
br label %exit
exit:
@ -25,15 +23,13 @@ exit:
ret void
}
define void @test_lds_var(i1 %i) {
define void @test_lds_var() {
; CHECK-LABEL: @test_lds_var(
; CHECK: store i32 10, i32 addrspace(3)* @lvar, align 4
; CHECK: [[LD:%.*]] = load i32, i32 addrspace(3)* @lvar, align 4
; CHECK: store volatile i32 [[LD]], i32* undef, align 4
;
entry:
br i1 %i, label %bb1, label %exit
bb1:
store i32 10, i32 addrspace(3)* @lvar
br label %exit
exit:

11
llvm/test/Transforms/GlobalOpt/stored-once-forward-value.ll
View File

@ -12,8 +12,10 @@ declare void @b()
define i1 @dom_const() {
; CHECK-LABEL: @dom_const(
; CHECK-NEXT: store i1 true, ptr @g1, align 1
; CHECK-NEXT: call void @b()
; CHECK-NEXT: ret i1 true
; CHECK-NEXT: [[R:%.*]] = load i1, ptr @g1, align 1
; CHECK-NEXT: ret i1 [[R]]
;
store i1 true, ptr @g1
call void @b()
@ -23,8 +25,10 @@ define i1 @dom_const() {
define i32 @dom_arg(i32 %a) {
; CHECK-LABEL: @dom_arg(
; CHECK-NEXT: store i32 [[A:%.*]], ptr @g2, align 4
; CHECK-NEXT: call void @b()
; CHECK-NEXT: ret i32 [[A:%.*]]
; CHECK-NEXT: [[R:%.*]] = load i32, ptr @g2, align 4
; CHECK-NEXT: ret i32 [[R]]
;
store i32 %a, ptr @g2
call void @b()
@ -70,7 +74,8 @@ define i1 @dom_multiple_function_loads() {
; CHECK-LABEL: @dom_multiple_function_loads(
; CHECK-NEXT: store i1 true, ptr @g5, align 1
; CHECK-NEXT: call void @b()
; CHECK-NEXT: ret i1 true
; CHECK-NEXT: [[R:%.*]] = load i1, ptr @g5, align 1
; CHECK-NEXT: ret i1 [[R]]
;
store i1 true, ptr @g5
call void @b()

1
llvm/test/Transforms/PhaseOrdering/recompute-globalsaa.ll
View File

@ -9,6 +9,7 @@
define i32 @main() {
; CHECK-LABEL: @main(
; CHECK-NEXT: entry:
; CHECK-NEXT: store i1 true, i1* @a, align 4
; CHECK-NEXT: [[TMP0:%.*]] = load i32*, i32** @e, align 8
; CHECK-NEXT: store i32 0, i32* [[TMP0]], align 4
; CHECK-NEXT: store i32* null, i32** @e, align 8