DanilM created this revision.
DanilM added reviewers: hfinkel, rjmccall, kosarev.
Herald added a subscriber: cfe-commits.
If SimplifyCFG attaches one block to another it removes all metadata from
instructions of a block that should be attached because it can be depended on
conditions that are changed during transformation.
In case of TBAA metadata, it looks too conservatively: data types of load/store
instructions cannot be changed during such transformations even if the pointed
data was changed.
So attached the patch saves TBAA tags from removing during SimplifyCFG
transformations.
Repository:
rC Clang
https://reviews.llvm.org/D44617
Files:
lib/Transforms/Utils/SimplifyCFG.cpp
test/Transforms/SimplifyCFG/basictest.ll
test/Transforms/SimplifyCFG/fold-two-entry-phi-tbaa.ll
test/Transforms/SimplifyCFG/speculate-tbaa.ll
Index: test/Transforms/SimplifyCFG/speculate-tbaa.ll
===================================================================
--- test/Transforms/SimplifyCFG/speculate-tbaa.ll
+++ test/Transforms/SimplifyCFG/speculate-tbaa.ll
@@ -0,0 +1,53 @@
+; RUN: opt < %s -S -simplifycfg | FileCheck %s
+
+; This test case was generated from speculate-tbaa.c:
+;
+; void foo(int *p1, int p2, int condition) {
+; *p1 = 100;
+; if (condition)
+; *p1 = p2;
+; }
+;
+; using
+; clang -cc1 -triple x86_64-linux-gnu -new-struct-path-tbaa -emit-llvm -o - -O3 -disable-llvm-passes speculate-tbaa.c | opt -mem2reg -S
+
+; ModuleID = '<stdin>'
+source_filename = "speculate-tbaa.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux-gnu"
+
+; Function Attrs: nounwind
+define void @foo(i32* %p1, i32 %p2, i32 %condition) #0 {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: store i32 100, i32* %p1, align 4, !tbaa [[TBAA_Tag:![0-9]+]]
+; CHECK-NEXT: %tobool = icmp ne i32 %condition, 0
+; CHECK-NEXT: %spec.store.select = select i1 %tobool, i32 %p2, i32 100
+; CHECK-NEXT: store i32 %spec.store.select, i32* %p1, align 4, !tbaa [[TBAA_Tag]]
+entry:
+ store i32 100, i32* %p1, align 4, !tbaa !2
+ %tobool = icmp ne i32 %condition, 0
+ br i1 %tobool, label %if.then, label %if.end
+
+if.then: ; preds = %entry
+ store i32 %p2, i32* %p1, align 4, !tbaa !2
+ br label %if.end
+
+if.end: ; preds = %if.then, %entry
+ ret void
+}
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+; CHECK-DAG: [[TBAA_Tag]] = !{[[TBAA_Type:![0-9]+]], [[TBAA_Type]], i64 0, i64 4}
+; CHECK-DAG: [[TBAA_Type]] = !{!{{[0-9]+}}, i64 4, !"int"}
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{!"clang version 7.0.0 (trunk 326065)"}
+!2 = !{!3, !3, i64 0, i64 4}
+!3 = !{!4, i64 4, !"int"}
+!4 = !{!5, i64 1, !"omnipotent char"}
+!5 = !{!"Simple C/C++ TBAA"}
+
Index: test/Transforms/SimplifyCFG/fold-two-entry-phi-tbaa.ll
===================================================================
--- test/Transforms/SimplifyCFG/fold-two-entry-phi-tbaa.ll
+++ test/Transforms/SimplifyCFG/fold-two-entry-phi-tbaa.ll
@@ -0,0 +1,75 @@
+; RUN: opt < %s -S -simplifycfg | FileCheck %s
+
+; This test case was generated from fold-two-entry-phi-tbaa.c:
+;
+; int foo(int p1, int p2, int p3) {
+; return p1 ? p1 : p2 ? p2 : p3;
+; }
+;
+; using
+; clang -cc1 -triple x86_64-linux-gnu -new-struct-path-tbaa -emit-llvm -o - -O3 -disable-llvm-passes fold-two-entry-phi-tbaa.c
+
+; ModuleID = 'fold-two-entry-phi-tbaa.c'
+source_filename = "fold-two-entry-phi-tbaa.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux-gnu"
+
+; Function Attrs: nounwind
+define i32 @foo(i32 %p1, i32 %p2, i32 %p3) #0 {
+entry:
+ %p1.addr = alloca i32, align 4
+ %p2.addr = alloca i32, align 4
+ %p3.addr = alloca i32, align 4
+ store i32 %p1, i32* %p1.addr, align 4, !tbaa !2
+ store i32 %p2, i32* %p2.addr, align 4, !tbaa !2
+ store i32 %p3, i32* %p3.addr, align 4, !tbaa !2
+ %0 = load i32, i32* %p1.addr, align 4, !tbaa !2
+ %tobool = icmp ne i32 %0, 0
+ br i1 %tobool, label %cond.true, label %cond.false
+
+cond.true: ; preds = %entry
+ %1 = load i32, i32* %p1.addr, align 4, !tbaa !2
+ br label %cond.end4
+
+; CHECK: cond.false:
+; CHECK-NEXT: %2 = load i32, i32* %p2.addr, align 4, !tbaa [[TBAA_Tag:![0-9]+]]
+; CHECK-NEXT: %tobool1 = icmp ne i32 %2, 0
+; CHECK-NEXT: %3 = load i32, i32* %p2.addr, align 4, !tbaa [[TBAA_Tag]]
+; CHECK-NEXT: %4 = load i32, i32* %p3.addr, align 4, !tbaa [[TBAA_Tag]]
+; CHECK-NEXT: %cond = select i1 %tobool1, i32 %3, i32 %4
+; CHECK-NEXT: br label %cond.end4
+cond.false: ; preds = %entry
+ %2 = load i32, i32* %p2.addr, align 4, !tbaa !2
+ %tobool1 = icmp ne i32 %2, 0
+ br i1 %tobool1, label %cond.true2, label %cond.false3
+
+cond.true2: ; preds = %cond.false
+ %3 = load i32, i32* %p2.addr, align 4, !tbaa !2
+ br label %cond.end
+
+cond.false3: ; preds = %cond.false
+ %4 = load i32, i32* %p3.addr, align 4, !tbaa !2
+ br label %cond.end
+
+cond.end: ; preds = %cond.false3, %cond.true2
+ %cond = phi i32 [ %3, %cond.true2 ], [ %4, %cond.false3 ]
+ br label %cond.end4
+
+cond.end4: ; preds = %cond.end, %cond.true
+ %cond5 = phi i32 [ %1, %cond.true ], [ %cond, %cond.end ]
+ ret i32 %cond5
+}
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+; CHECK-DAG: [[TBAA_Tag]] = !{[[TBAA_Type:![0-9]+]], [[TBAA_Type]], i64 0, i64 4}
+; CHECK-DAG: [[TBAA_Type]] = !{!{{[0-9]+}}, i64 4, !"int"}
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{!"clang version 7.0.0 (trunk 326065)"}
+!2 = !{!3, !3, i64 0, i64 4}
+!3 = !{!4, i64 4, !"int"}
+!4 = !{!5, i64 1, !"omnipotent char"}
+!5 = !{!"Simple C/C++ TBAA"}
Index: test/Transforms/SimplifyCFG/basictest.ll
===================================================================
--- test/Transforms/SimplifyCFG/basictest.ll
+++ test/Transforms/SimplifyCFG/basictest.ll
@@ -98,15 +98,15 @@
; CHECK: alloca i8, align 1
; CHECK-NEXT: call i8 @test6g
; CHECK-NEXT: icmp eq i8 %tmp, 0
-; CHECK-NEXT: load i8, i8* %r, align 1, !dbg !{{[0-9]+$}}
+; CHECK-NEXT: load i8, i8* %r, align 1, !dbg !{{[0-9]+}}, !tbaa [[TBAA_Tag:![0-9]+]]
bb0:
%r = alloca i8, align 1
%tmp = call i8 @test6g(i8* %r)
%tmp1 = icmp eq i8 %tmp, 0
br i1 %tmp1, label %bb2, label %bb1
bb1:
- %tmp3 = load i8, i8* %r, align 1, !range !2, !tbaa !10, !dbg !5
+ %tmp3 = load i8, i8* %r, align 1, !range !2, !tbaa !0, !dbg !5
%tmp4 = icmp eq i8 %tmp3, 1
br i1 %tmp4, label %bb2, label %bb3
bb2:
@@ -120,14 +120,15 @@
!llvm.dbg.cu = !{!3}
!llvm.module.flags = !{!8, !9}
-!0 = !{!10, !10, i64 0}
-!1 = !{!"foo"}
+; CHECK-DAG: [[TBAA_Tag]] = !{[[TBAA_Type:![0-9]+]], [[TBAA_Type]], i64 0, i64 1}
+!0 = !{!10, !10, i64 0, i64 1}
+!1 = !{!"TBAA root"}
!2 = !{i8 0, i8 2}
!3 = distinct !DICompileUnit(language: DW_LANG_C99, file: !7, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !4)
!4 = !{}
!5 = !DILocation(line: 23, scope: !6)
!6 = distinct !DISubprogram(name: "foo", scope: !3, file: !7, line: 1, type: !DISubroutineType(types: !4), isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !3, variables: !4)
!7 = !DIFile(filename: "foo.c", directory: "/")
!8 = !{i32 2, !"Dwarf Version", i32 2}
!9 = !{i32 2, !"Debug Info Version", i32 3}
-!10 = !{!"scalar type", !1}
+!10 = !{!1, i64 1, !"scalar type"}
Index: lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyCFG.cpp
+++ lib/Transforms/Utils/SimplifyCFG.cpp
@@ -153,6 +153,11 @@
// switch for that PHI.
using SwitchCaseResultsTy = SmallVector<std::pair<PHINode *, Constant *>, 4>;
+// When SimplifyCFG attaches one block to another, it removes metadata from
+// instructions that will be attached. This array contains metadata names that
+// should be remained.
+const unsigned ValidMetadataAfterBlockMerging[] = { LLVMContext::MD_tbaa };
+
/// ValueEqualityComparisonCase - Represents a case of a switch.
struct ValueEqualityComparisonCase {
ConstantInt *Value;
@@ -2077,8 +2082,8 @@
// Metadata can be dependent on the condition we are hoisting above.
// Conservatively strip all metadata on the instruction.
for (auto &I : *ThenBB)
- I.dropUnknownNonDebugMetadata();
-
+ I.dropUnknownNonDebugMetadata(ValidMetadataAfterBlockMerging);
+
// Hoist the instructions.
BB->getInstList().splice(BI->getIterator(), ThenBB->getInstList(),
ThenBB->begin(), std::prev(ThenBB->end()));
@@ -2375,14 +2380,14 @@
// conditional parts of the if's up to the dominating block.
if (IfBlock1) {
for (auto &I : *IfBlock1)
- I.dropUnknownNonDebugMetadata();
+ I.dropUnknownNonDebugMetadata(ValidMetadataAfterBlockMerging);
DomBlock->getInstList().splice(InsertPt->getIterator(),
IfBlock1->getInstList(), IfBlock1->begin(),
IfBlock1->getTerminator()->getIterator());
}
if (IfBlock2) {
for (auto &I : *IfBlock2)
- I.dropUnknownNonDebugMetadata();
+ I.dropUnknownNonDebugMetadata(ValidMetadataAfterBlockMerging);
DomBlock->getInstList().splice(InsertPt->getIterator(),
IfBlock2->getInstList(), IfBlock2->begin(),
IfBlock2->getTerminator()->getIterator());
@@ -2702,7 +2707,7 @@
// only given the branch precondition.
// For an analogous reason, we must also drop all the metadata whose
// semantics we don't understand.
- NewBonusInst->dropUnknownNonDebugMetadata();
+ NewBonusInst->dropUnknownNonDebugMetadata(ValidMetadataAfterBlockMerging);
PredBlock->getInstList().insert(PBI->getIterator(), NewBonusInst);
NewBonusInst->takeName(&*BonusInst);
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