fhahn created this revision.
fhahn added reviewers: jdoerfert, rjmccall, xbolva00, atmnpatel, aaron.ballman,
rsmith.
fhahn requested review of this revision.
Herald added a project: clang.
Currently Clang does not add mustprogress to inifinite loops with a
known constant condition, matching C11 behavior. The forward progress
guarantee in C++11 and later should allow us to add mustprogress to any
loop (http://eel.is/c++draft/intro.progress#1).
This allows us to simplify the code dealing with adding mustprogress a
bit.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D96418
Files:
clang/lib/CodeGen/CGStmt.cpp
clang/lib/CodeGen/CodeGenFunction.cpp
clang/lib/CodeGen/CodeGenFunction.h
clang/test/CodeGen/attr-mustprogress.c
clang/test/CodeGenCXX/attr-mustprogress.cpp
Index: clang/test/CodeGenCXX/attr-mustprogress.cpp
===================================================================
--- clang/test/CodeGenCXX/attr-mustprogress.cpp
+++ clang/test/CodeGenCXX/attr-mustprogress.cpp
@@ -10,27 +10,27 @@
// CHECK: datalayout
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z2f0v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %for.cond
// CHECK: for.cond:
// CXX98-NOT: br {{.*}} llvm.loop
-// CXX11-NOT: br {{.*}} llvm.loop
+// CXX11-NEXT: br label %for.cond, !llvm.loop [[LOOP1:!.*]]
void f0() {
for (; ;) ;
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z2f1v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %for.cond
// CHECK: for.cond:
// CHECK-NEXT: br i1 true, label %for.body, label %for.end
// CHECK: for.body:
-// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX98-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %for.cond, !llvm.loop [[LOOP2:!.*]]
// CHECK: for.end:
// CHECK-NEXT: ret void
//
@@ -50,8 +50,8 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label %for.body, label %for.end
// CHECK: for.body:
-// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11: br label %for.cond, !llvm.loop [[LOOP1:!.*]]
+// CXX98-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %for.cond, !llvm.loop [[LOOP3:!.*]]
// CHECK: for.end:
// CHECK-NEXT: ret void
//
@@ -61,7 +61,7 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z1Fv(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %for.cond
@@ -69,7 +69,7 @@
// CHECK-NEXT: br i1 true, label %for.body, label %for.end
// CHECK: for.body:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %for.cond, !llvm.loop [[LOOP4:!.*]]
// CHECK: for.end:
// CHECK-NEXT: br label %for.cond1
// CHECK: for.cond1:
@@ -78,8 +78,8 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label %for.body2, label %for.end3
// CHECK: for.body2:
-// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11: br label %for.cond1, !llvm.loop [[LOOP2:!.*]]
+// CXX98-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %for.cond1, !llvm.loop [[LOOP5:!.*]]
// CHECK: for.end3:
// CHECK-NEXT: ret void
//
@@ -102,14 +102,14 @@
// CHECK-NEXT: br i1 [[CMP]], label %for.body, label %for.end
// CHECK: for.body:
// CXX98_NOT: br {{.*}} !llvm.loop
-// CXX11-NEXT: br label %for.cond, !llvm.loop
+// CXX11-NEXT: br label %for.cond, !llvm.loop [[LOOP6:!.*]]
// CHECK: for.end:
// CHECK-NEXT: br label %for.cond1
// CHECK: for.cond1:
// CHECK-NEXT: br i1 true, label %for.body2, label %for.end3
// CHECK: for.body2:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %for.cond1, !llvm.loop [[LOOP7:!.*]]
// CHECK: for.end3:
// CHECK-NEXT: ret void
//
@@ -121,13 +121,13 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z2w1v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %while.body
// CHECK: while.body:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %while.body, !llvm.loop [[LOOP8:!.*]]
//
void w1() {
while (1)
@@ -146,7 +146,7 @@
// CHECK-NEXT: br i1 [[CMP]], label %while.body, label %while.end
// CHECK: while.body:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NEXT: br label %while.cond, !llvm.loop [[LOOP3:!.*]]
+// CXX11-NEXT: br label %while.cond, !llvm.loop [[LOOP9:!.*]]
// CHECK: while.end:
// CHECK-NEXT: ret void
//
@@ -156,7 +156,7 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z1Wv(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %while.cond
@@ -167,12 +167,12 @@
// CHECK-NEXT: br i1 [[CMP]], label %while.body, label %while.end
// CHECK: while.body:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NEXT: br label %while.cond, !llvm.loop [[LOOP4:!.*]]
+// CXX11-NEXT: br label %while.cond, !llvm.loop [[LOOP10:!.*]]
// CHECK: while.end:
// CHECK-NEXT: br label %while.body2
// CHECK: while.body2:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %while.body2, !llvm.loop [[LOOP11:!.*]]
//
void W() {
while (a == b)
@@ -182,13 +182,13 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z2W2v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %while.body
// CHECK: while.body:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br label %while.body, !llvm.loop [[LOOP12:!.*]]
//
void W2() {
while (1)
@@ -198,7 +198,7 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z2d1v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %do.body
@@ -206,7 +206,7 @@
// CHECK-NEXT: br label %do.cond
// CHECK: do.cond:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br i1 true, label %do.body, label %do.end, !llvm.loop [[LOOP13:!.*]]
// CHECK: do.end:
// CHECK-NEXT: ret void
//
@@ -228,7 +228,7 @@
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NEXT: br i1 [[CMP]], label %do.body, label %do.end, !llvm.loop [[LOOP5:!.*]]
+// CXX11-NEXT: br i1 [[CMP]], label %do.body, label %do.end, !llvm.loop [[LOOP14:!.*]]
// CHECK: do.end:
// CHECK-NEXT: ret void
//
@@ -239,7 +239,7 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z1Dv(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %do.body
@@ -247,7 +247,7 @@
// CHECK-NEXT: br label %do.cond
// CHECK: do.cond:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br i1 true, label %do.body, label %do.end, !llvm.loop [[LOOP15:!.*]]
// CHECK: do.end:
// CHECK-NEXT: br label %do.body1
// CHECK: do.body1:
@@ -257,7 +257,7 @@
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NEXT: br i1 [[CMP]], label %do.body1, label %do.end3, !llvm.loop [[LOOP6:!.*]]
+// CXX11-NEXT: br i1 [[CMP]], label %do.body1, label %do.end3, !llvm.loop [[LOOP16:!.*]]
// CHECK: do.end3:
// CHECK-NEXT: ret void
//
@@ -271,7 +271,7 @@
}
// CXX98-NOT: mustprogress
-// CXX11-NOT: mustprogress
+// CXX11: mustprogress
// CHECK-LABEL: @_Z2D2v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %do.body
@@ -282,14 +282,14 @@
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NEXT: br i1 [[CMP]], label %do.body, label %do.end, !llvm.loop [[LOOP7:!.*]]
+// CXX11-NEXT: br i1 [[CMP]], label %do.body, label %do.end, !llvm.loop [[LOOP17:!.*]]
// CHECK: do.end:
// CHECK-NEXT: br label %do.body1
// CHECK: do.body1:
// CHECK-NEXT: br label %do.cond2
// CHECK: do.cond2:
// CXX98-NOT: br {{.*}}, !llvm.loop
-// CXX11-NOT: br {{.*}}, !llvm.loop
+// CXX11-NEXT: br i1 true, label %do.body1, label %do.end3, !llvm.loop [[LOOP18:!.*]]
// CHECK: do.end3:
// CHECK-NEXT: ret void
//
@@ -302,7 +302,6 @@
while (1);
}
-
// CXX11: [[LOOP1]] = distinct !{[[LOOP1]], [[MP:!.*]]}
// CXX11: [[MP]] = !{!"llvm.loop.mustprogress"}
// CXX11: [[LOOP2]] = distinct !{[[LOOP2]], [[MP]]}
@@ -311,3 +310,14 @@
// CXX11: [[LOOP5]] = distinct !{[[LOOP5]], [[MP]]}
// CXX11: [[LOOP6]] = distinct !{[[LOOP6]], [[MP]]}
// CXX11: [[LOOP7]] = distinct !{[[LOOP7]], [[MP]]}
+// CXX11: [[LOOP8]] = distinct !{[[LOOP8]], [[MP]]}
+// CXX11: [[LOOP9]] = distinct !{[[LOOP9]], [[MP]]}
+// CXX11: [[LOOP10]] = distinct !{[[LOOP10]], [[MP]]}
+// CXX11: [[LOOP11]] = distinct !{[[LOOP11]], [[MP]]}
+// CXX11: [[LOOP12]] = distinct !{[[LOOP12]], [[MP]]}
+// CXX11: [[LOOP13]] = distinct !{[[LOOP13]], [[MP]]}
+// CXX11: [[LOOP14]] = distinct !{[[LOOP14]], [[MP]]}
+// CXX11: [[LOOP15]] = distinct !{[[LOOP15]], [[MP]]}
+// CXX11: [[LOOP16]] = distinct !{[[LOOP16]], [[MP]]}
+// CXX11: [[LOOP17]] = distinct !{[[LOOP17]], [[MP]]}
+// CXX11: [[LOOP18]] = distinct !{[[LOOP18]], [[MP]]}
Index: clang/test/CodeGen/attr-mustprogress.c
===================================================================
--- clang/test/CodeGen/attr-mustprogress.c
+++ clang/test/CodeGen/attr-mustprogress.c
@@ -104,7 +104,7 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label %while.body, label %while.end
// CHECK: while.body:
-// C11: br label %while.cond, [[LOOP5:!llvm.loop !.*]]
+// C11: br label %while.cond, !llvm.loop [[LOOP3:!.*]]
// C99-NOT: br {{.*}}, !llvm.loop
// CHECK: while.end:
// CHECK-NEXT: ret void
@@ -125,7 +125,9 @@
// CHECK-NEXT: br i1 [[CMP]], label %while.body, label %while.end
// CHECK: while.body:
// C99-NOT: br {{.*}} !llvm.loop
-// C11: br label %while.body, !llvm.loop [[LOOP3:!.*]]
+// C11-NEXT: br label %while.cond, !llvm.loop [[LOOP4:!.*]]
+// CHECK: while.body2:
+// CHECK-NOT: br {{.*}} !llvm.loop
//
void W() {
while (a == b) {
@@ -161,7 +163,7 @@
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// C99-NOT: br {{.*}}, !llvm.loop
-// C11: br i1 [[CMP]], label %do.body, label %do.end, !llvm.loop [[LOOP4:!.*]]
+// C11: br i1 [[CMP]], label %do.body, label %do.end, !llvm.loop [[LOOP5:!.*]]
// CHECK: do.end:
// CHECK-NEXT: ret void
//
@@ -187,7 +189,7 @@
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// C99-NOT: br {{.*}}, !llvm.loop
-// C11: br i1 [[CMP]], label %do.body1, label %do.end3, !llvm.loop [[LOOP5:!.*]]
+// C11: br i1 [[CMP]], label %do.body1, label %do.end3, !llvm.loop [[LOOP6:!.*]]
// CHECK: do.end3:
// CHECK-NEXT: ret void
//
@@ -204,3 +206,4 @@
// C11: [[LOOP3]] = distinct !{[[LOOP3]], [[MP]]}
// C11: [[LOOP4]] = distinct !{[[LOOP4]], [[MP]]}
// C11: [[LOOP5]] = distinct !{[[LOOP5]], [[MP]]}
+// C11: [[LOOP6]] = distinct !{[[LOOP6]], [[MP]]}
Index: clang/lib/CodeGen/CodeGenFunction.h
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.h
+++ clang/lib/CodeGen/CodeGenFunction.h
@@ -505,23 +505,23 @@
/// True if the current function should be marked mustprogress.
bool FnIsMustProgress = false;
- /// True if the C++ Standard Requires Progress.
- bool CPlusPlusWithProgress() {
+ /// Returns true if the function must make progress.
+ bool functionMustProgress() {
return getLangOpts().CPlusPlus11 || getLangOpts().CPlusPlus14 ||
getLangOpts().CPlusPlus17 || getLangOpts().CPlusPlus20;
}
- /// True if the C Standard Requires Progress.
- bool CWithProgress() {
+ /// Returns true if either the containing function must make progress.
+ /// Otherwise return false if the loop condition is a known constant and true
+ /// if the language standard is C11+.
+ bool loopMustProgress(bool HasConstantCond) {
+ if (functionMustProgress())
+ return true;
+ if (HasConstantCond)
+ return false;
return getLangOpts().C11 || getLangOpts().C17 || getLangOpts().C2x;
}
- /// True if the language standard requires progress in functions or
- /// in infinite loops with non-constant conditionals.
- bool LanguageRequiresProgress() {
- return CWithProgress() || CPlusPlusWithProgress();
- }
-
const CodeGen::CGBlockInfo *BlockInfo = nullptr;
llvm::Value *BlockPointer = nullptr;
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -1177,9 +1177,6 @@
void CodeGenFunction::EmitFunctionBody(const Stmt *Body) {
incrementProfileCounter(Body);
- if (CPlusPlusWithProgress())
- FnIsMustProgress = true;
-
if (const CompoundStmt *S = dyn_cast<CompoundStmt>(Body))
EmitCompoundStmtWithoutScope(*S);
else
@@ -1187,7 +1184,7 @@
// This is checked after emitting the function body so we know if there
// are any permitted infinite loops.
- if (FnIsMustProgress)
+ if (functionMustProgress())
CurFn->addFnAttr(llvm::Attribute::MustProgress);
}
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -791,20 +791,14 @@
// while(1) is common, avoid extra exit blocks. Be sure
// to correctly handle break/continue though.
- bool EmitBoolCondBranch = true;
- bool LoopMustProgress = false;
- if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) {
- if (C->isOne()) {
- EmitBoolCondBranch = false;
- FnIsMustProgress = false;
- }
- } else if (LanguageRequiresProgress())
- LoopMustProgress = true;
-
+ llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal);
+ bool EmitBoolCondBranch = !C || !C->isOne();
+ bool CondIsConst = C;
const SourceRange &R = S.getSourceRange();
LoopStack.push(LoopHeader.getBlock(), CGM.getContext(), CGM.getCodeGenOpts(),
WhileAttrs, SourceLocToDebugLoc(R.getBegin()),
- SourceLocToDebugLoc(R.getEnd()), LoopMustProgress);
+ SourceLocToDebugLoc(R.getEnd()),
+ loopMustProgress(CondIsConst));
// As long as the condition is true, go to the loop body.
llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
@@ -892,20 +886,15 @@
// "do {} while (0)" is common in macros, avoid extra blocks. Be sure
// to correctly handle break/continue though.
- bool EmitBoolCondBranch = true;
- bool LoopMustProgress = false;
- if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) {
- if (C->isZero())
- EmitBoolCondBranch = false;
- else if (C->isOne())
- FnIsMustProgress = false;
- } else if (LanguageRequiresProgress())
- LoopMustProgress = true;
+ llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal);
+ bool CondIsConst = C;
+ bool EmitBoolCondBranch = !C || !C->isZero();
const SourceRange &R = S.getSourceRange();
LoopStack.push(LoopBody, CGM.getContext(), CGM.getCodeGenOpts(), DoAttrs,
SourceLocToDebugLoc(R.getBegin()),
- SourceLocToDebugLoc(R.getEnd()), LoopMustProgress);
+ SourceLocToDebugLoc(R.getEnd()),
+ loopMustProgress(CondIsConst));
// As long as the condition is true, iterate the loop.
if (EmitBoolCondBranch) {
@@ -943,20 +932,15 @@
llvm::BasicBlock *CondBlock = Continue.getBlock();
EmitBlock(CondBlock);
- bool LoopMustProgress = false;
Expr::EvalResult Result;
- if (LanguageRequiresProgress()) {
- if (!S.getCond()) {
- FnIsMustProgress = false;
- } else if (!S.getCond()->EvaluateAsInt(Result, getContext())) {
- LoopMustProgress = true;
- }
- }
+ bool CondIsConst =
+ !S.getCond() || S.getCond()->EvaluateAsInt(Result, getContext());
const SourceRange &R = S.getSourceRange();
LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
SourceLocToDebugLoc(R.getBegin()),
- SourceLocToDebugLoc(R.getEnd()), LoopMustProgress);
+ SourceLocToDebugLoc(R.getEnd()),
+ loopMustProgress(CondIsConst));
// If the for loop doesn't have an increment we can just use the
// condition as the continue block. Otherwise we'll need to create
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