[llvm] 6f348b1 - [GlobalOpt] Perform store->dominated load forwarding for stored once globals
Arthur Eubanks via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 19 10:27:30 PDT 2022
Author: Arthur Eubanks
Date: 2022-06-19T10:27:20-07:00
New Revision: 6f348b146b69a50d5fb1b9fbfd14bc1d204e45c4
URL: https://github.com/llvm/llvm-project/commit/6f348b146b69a50d5fb1b9fbfd14bc1d204e45c4
DIFF: https://github.com/llvm/llvm-project/commit/6f348b146b69a50d5fb1b9fbfd14bc1d204e45c4.diff
LOG: [GlobalOpt] Perform store->dominated load forwarding for stored once globals
Compile time tracker:
https://llvm-compile-time-tracker.com/compare.php?from=1e556f459b44dd0ca4073e932f66ecb6f40fe31a&to=6d7bed4e1e72c6a8592748626091274209740a40&stat=instructions
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D128128
Added:
Modified:
llvm/lib/Transforms/IPO/GlobalOpt.cpp
llvm/test/Transforms/GlobalOpt/malloc-promote-1-no-null-opt.ll
llvm/test/Transforms/GlobalOpt/malloc-promote-2-no-null-opt.ll
llvm/test/Transforms/GlobalOpt/malloc-promote-3.ll
llvm/test/Transforms/GlobalOpt/shrink-global-to-bool-check-debug.ll
llvm/test/Transforms/GlobalOpt/shrink-global-to-bool.ll
llvm/test/Transforms/GlobalOpt/stored-once-forward-value.ll
llvm/test/Transforms/PhaseOrdering/recompute-globalsaa.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index a2b47166cdfc4..6ea2242a88cbc 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1438,6 +1438,37 @@ 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
@@ -1597,6 +1628,10 @@ 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 &&
diff --git a/llvm/test/Transforms/GlobalOpt/malloc-promote-1-no-null-opt.ll b/llvm/test/Transforms/GlobalOpt/malloc-promote-1-no-null-opt.ll
index 4cbe837669900..ccda0b8144d87 100644
--- a/llvm/test/Transforms/GlobalOpt/malloc-promote-1-no-null-opt.ll
+++ b/llvm/test/Transforms/GlobalOpt/malloc-promote-1-no-null-opt.ll
@@ -12,8 +12,7 @@ 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: [[GV:%.*]] = load i32*, i32** @G, align 8
-; CHECK-NEXT: store i32 0, i32* [[GV]], align 4
+; CHECK-NEXT: store i32 0, i32* [[P]], align 4
; CHECK-NEXT: ret void
;
%malloccall = tail call i8* @malloc(i64 4)
diff --git a/llvm/test/Transforms/GlobalOpt/malloc-promote-2-no-null-opt.ll b/llvm/test/Transforms/GlobalOpt/malloc-promote-2-no-null-opt.ll
index 0b31aaf6a2825..9c17c833a8093 100644
--- a/llvm/test/Transforms/GlobalOpt/malloc-promote-2-no-null-opt.ll
+++ b/llvm/test/Transforms/GlobalOpt/malloc-promote-2-no-null-opt.ll
@@ -12,8 +12,7 @@ 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: [[GV:%.*]] = load i32*, i32** @G, align 8
-; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[GV]], i32 40
+; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[P]], i32 40
; CHECK-NEXT: store i32 20, i32* [[GVE]], align 4
; CHECK-NEXT: ret void
;
diff --git a/llvm/test/Transforms/GlobalOpt/malloc-promote-3.ll b/llvm/test/Transforms/GlobalOpt/malloc-promote-3.ll
index fe7b4753dd5cc..2a9940296c1cb 100644
--- a/llvm/test/Transforms/GlobalOpt/malloc-promote-3.ll
+++ b/llvm/test/Transforms/GlobalOpt/malloc-promote-3.ll
@@ -12,8 +12,7 @@ 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: [[GV:%.*]] = load i32*, i32** @G, align 8
-; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[GV]], i32 40
+; CHECK-NEXT: [[GVE:%.*]] = getelementptr i32, i32* [[P]], i32 40
; CHECK-NEXT: store i32 20, i32* [[GVE]], align 4
; CHECK-NEXT: ret void
;
diff --git a/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool-check-debug.ll b/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool-check-debug.ll
index da396363547fd..1c917413c6f00 100644
--- a/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool-check-debug.ll
+++ b/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool-check-debug.ll
@@ -2,21 +2,24 @@
@foo = internal global i32 0, align 4
-define dso_local i32 @bar() {
+define void @store() {
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: ![[DbgLocStore]] = !DILocation(line: 1,
-;CHECK: ![[DbgLocLoadSel]] = !DILocation(line: 2,
-;CHECK: ![[DbgLocRet]] = !DILocation(line: 3,
+;CHECK: ![[DbgLocLoadSel]] = !DILocation(line: 3,
+;CHECK: ![[DbgLocRet]] = !DILocation(line: 4,
diff --git a/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool.ll b/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool.ll
index 74c35466992bf..bdd515bf2e557 100644
--- a/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool.ll
+++ b/llvm/test/Transforms/GlobalOpt/shrink-global-to-bool.ll
@@ -10,11 +10,13 @@
; 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() {
+define void @test_global_var(i1 %i) {
; 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:
@@ -23,13 +25,15 @@ exit:
ret void
}
-define void @test_lds_var() {
+define void @test_lds_var(i1 %i) {
; 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:
diff --git a/llvm/test/Transforms/GlobalOpt/stored-once-forward-value.ll b/llvm/test/Transforms/GlobalOpt/stored-once-forward-value.ll
index b043a03608a7c..33a389176d154 100644
--- a/llvm/test/Transforms/GlobalOpt/stored-once-forward-value.ll
+++ b/llvm/test/Transforms/GlobalOpt/stored-once-forward-value.ll
@@ -12,10 +12,8 @@ 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: [[R:%.*]] = load i1, ptr @g1, align 1
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 true
;
store i1 true, ptr @g1
call void @b()
@@ -25,10 +23,8 @@ 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: [[R:%.*]] = load i32, ptr @g2, align 4
-; CHECK-NEXT: ret i32 [[R]]
+; CHECK-NEXT: ret i32 [[A:%.*]]
;
store i32 %a, ptr @g2
call void @b()
@@ -74,8 +70,7 @@ 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: [[R:%.*]] = load i1, ptr @g5, align 1
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 true
;
store i1 true, ptr @g5
call void @b()
diff --git a/llvm/test/Transforms/PhaseOrdering/recompute-globalsaa.ll b/llvm/test/Transforms/PhaseOrdering/recompute-globalsaa.ll
index 3dbddbdb96faa..f4290c64a773a 100644
--- a/llvm/test/Transforms/PhaseOrdering/recompute-globalsaa.ll
+++ b/llvm/test/Transforms/PhaseOrdering/recompute-globalsaa.ll
@@ -9,7 +9,6 @@
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
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