atmnpatel created this revision.
atmnpatel added reviewers: fhahn, jdoerfert, xbolva00.
atmnpatel requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Currently, clang does not emit the `mustprogress` loop or function
attribute for loops with non-zero constant conditionals. Based on recent
discussion in D86844 <https://reviews.llvm.org/D86844> and D86841
<https://reviews.llvm.org/D86841>, it seems that it would be preferable to
emit these attributes to adhere more tightly to the C++ standard as gcc
does.
I will be pushing a patch to add `-ffinite-loops` and `-fno-finite-loops` to
clang to provide more control over this momentarily.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D94366
Files:
clang/lib/CodeGen/CGStmt.cpp
clang/test/CodeGen/attr-mustprogress-1.cpp
Index: clang/test/CodeGen/attr-mustprogress-1.cpp
===================================================================
--- clang/test/CodeGen/attr-mustprogress-1.cpp
+++ clang/test/CodeGen/attr-mustprogress-1.cpp
@@ -7,24 +7,25 @@
int a = 0;
int b = 0;
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z2f0v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[FOR_COND:%.*]]
// CHECK: for.cond:
-// CHECK-NOT: br label [[FOR_COND]], !llvm.loop !{{.*}}
+// CHECK-NEXT: br label [[FOR_COND]], [[LOOP2:!llvm.loop !.*]]
+//
void f0() {
for (; ;) ;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone 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:
-// CHECK-NEXT: br label [[FOR_COND]]
+// CHECK-NEXT: br label [[FOR_COND]], [[LOOP4:!llvm.loop !.*]]
// CHECK: for.end:
// CHECK-NEXT: ret void
//
@@ -43,7 +44,7 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY:%.*]], label [[FOR_END:%.*]]
// CHECK: for.body:
-// CHECK-NEXT: br label [[FOR_COND]], [[LOOP2:!llvm.loop !.*]]
+// CHECK-NEXT: br label [[FOR_COND]], [[LOOP5:!llvm.loop !.*]]
// CHECK: for.end:
// CHECK-NEXT: ret void
//
@@ -52,14 +53,14 @@
;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z1Fv(
// 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:
-// CHECK-NEXT: br label [[FOR_COND]]
+// CHECK-NEXT: br label [[FOR_COND]], [[LOOP6:!llvm.loop !.*]]
// CHECK: for.end:
// CHECK-NEXT: br label [[FOR_COND1:%.*]]
// CHECK: for.cond1:
@@ -68,7 +69,7 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY2:%.*]], label [[FOR_END3:%.*]]
// CHECK: for.body2:
-// CHECK-NEXT: br label [[FOR_COND1]], [[LOOP4:!llvm.loop !.*]]
+// CHECK-NEXT: br label [[FOR_COND1]], [[LOOP7:!llvm.loop !.*]]
// CHECK: for.end3:
// CHECK-NEXT: ret void
//
@@ -79,7 +80,7 @@
;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z2F2v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[FOR_COND:%.*]]
@@ -89,13 +90,13 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY:%.*]], label [[FOR_END:%.*]]
// CHECK: for.body:
-// CHECK-NEXT: br label [[FOR_COND]], [[LOOP5:!llvm.loop !.*]]
+// CHECK-NEXT: br label [[FOR_COND]], [[LOOP8:!llvm.loop !.*]]
// 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:
-// CHECK-NEXT: br label [[FOR_COND1]]
+// CHECK-NEXT: br label [[FOR_COND1]], [[LOOP9:!llvm.loop !.*]]
// CHECK: for.end3:
// CHECK-NEXT: ret void
//
@@ -106,7 +107,7 @@
;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z2w1v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[WHILE_BODY:%.*]]
@@ -128,7 +129,7 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label [[WHILE_BODY:%.*]], label [[WHILE_END:%.*]]
// CHECK: while.body:
-// CHECK-NEXT: br label [[WHILE_COND]], [[LOOP6:!llvm.loop !.*]]
+// CHECK-NEXT: br label [[WHILE_COND]], [[LOOP10:!llvm.loop !.*]]
// CHECK: while.end:
// CHECK-NEXT: ret void
//
@@ -137,7 +138,7 @@
;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z1Wv(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[WHILE_COND:%.*]]
@@ -147,7 +148,7 @@
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
// CHECK-NEXT: br i1 [[CMP]], label [[WHILE_BODY:%.*]], label [[WHILE_END:%.*]]
// CHECK: while.body:
-// CHECK-NEXT: br label [[WHILE_COND]], [[LOOP7:!llvm.loop !.*]]
+// CHECK-NEXT: br label [[WHILE_COND]], [[LOOP11:!llvm.loop !.*]]
// CHECK: while.end:
// CHECK-NEXT: br label [[WHILE_BODY2:%.*]]
// CHECK: while.body2:
@@ -160,7 +161,7 @@
;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z2W2v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[WHILE_BODY:%.*]]
@@ -174,14 +175,14 @@
;
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z2d1v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[DO_BODY:%.*]]
// CHECK: do.body:
// CHECK-NEXT: br label [[DO_COND:%.*]]
// CHECK: do.cond:
-// CHECK-NEXT: br i1 true, label [[DO_BODY]], label [[DO_END:%.*]]
+// CHECK-NEXT: br i1 true, label [[DO_BODY]], label [[DO_END:%.*]], [[LOOP12:!llvm.loop !.*]]
// CHECK: do.end:
// CHECK-NEXT: ret void
//
@@ -201,7 +202,7 @@
// CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* @a, align 4
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
-// CHECK-NEXT: br i1 [[CMP]], label [[DO_BODY]], label [[DO_END:%.*]], [[LOOP8:!llvm.loop !.*]]
+// CHECK-NEXT: br i1 [[CMP]], label [[DO_BODY]], label [[DO_END:%.*]], [[LOOP13:!llvm.loop !.*]]
// CHECK: do.end:
// CHECK-NEXT: ret void
//
@@ -211,14 +212,14 @@
while (a == b);
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z1Dv(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[DO_BODY:%.*]]
// CHECK: do.body:
// CHECK-NEXT: br label [[DO_COND:%.*]]
// CHECK: do.cond:
-// CHECK-NEXT: br i1 true, label [[DO_BODY]], label [[DO_END:%.*]]
+// CHECK-NEXT: br i1 true, label [[DO_BODY]], label [[DO_END:%.*]], [[LOOP14:!llvm.loop !.*]]
// CHECK: do.end:
// CHECK-NEXT: br label [[DO_BODY1:%.*]]
// CHECK: do.body1:
@@ -227,7 +228,7 @@
// CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* @a, align 4
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
-// CHECK-NEXT: br i1 [[CMP]], label [[DO_BODY1]], label [[DO_END3:%.*]], [[LOOP9:!llvm.loop !.*]]
+// CHECK-NEXT: br i1 [[CMP]], label [[DO_BODY1]], label [[DO_END3:%.*]], [[LOOP15:!llvm.loop !.*]]
// CHECK: do.end3:
// CHECK-NEXT: ret void
//
@@ -240,7 +241,7 @@
while (a == b);
}
-// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK: Function Attrs: noinline nounwind optnone mustprogress
// CHECK-LABEL: @_Z2D2v(
// CHECK-NEXT: entry:
// CHECK-NEXT: br label [[DO_BODY:%.*]]
@@ -250,13 +251,13 @@
// CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* @a, align 4
// CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* @b, align 4
// CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
-// CHECK-NEXT: br i1 [[CMP]], label [[DO_BODY]], label [[DO_END:%.*]], [[LOOP10:!llvm.loop !.*]]
+// CHECK-NEXT: br i1 [[CMP]], label [[DO_BODY]], label [[DO_END:%.*]], [[LOOP16:!llvm.loop !.*]]
// CHECK: do.end:
// CHECK-NEXT: br label [[DO_BODY1:%.*]]
// CHECK: do.body1:
// CHECK-NEXT: br label [[DO_COND2:%.*]]
// CHECK: do.cond2:
-// CHECK-NEXT: br i1 true, label [[DO_BODY1]], label [[DO_END3:%.*]]
+// CHECK-NEXT: br i1 true, label [[DO_BODY1]], label [[DO_END3:%.*]], [[LOOP17:!llvm.loop !.*]]
// CHECK: do.end3:
// CHECK-NEXT: ret void
//
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -796,7 +796,8 @@
if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) {
if (C->isOne()) {
EmitBoolCondBranch = false;
- FnIsMustProgress = false;
+ if (CWithProgress())
+ FnIsMustProgress = false;
}
} else if (LanguageRequiresProgress())
LoopMustProgress = true;
@@ -897,8 +898,10 @@
if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) {
if (C->isZero())
EmitBoolCondBranch = false;
- else if (C->isOne())
+ else if (C->isOne() && CWithProgress())
FnIsMustProgress = false;
+ else if (CPlusPlusWithProgress())
+ LoopMustProgress = true;
} else if (LanguageRequiresProgress())
LoopMustProgress = true;
@@ -945,12 +948,13 @@
bool LoopMustProgress = false;
Expr::EvalResult Result;
+
if (LanguageRequiresProgress()) {
- if (!S.getCond()) {
+ if (!S.getCond() && CWithProgress())
FnIsMustProgress = false;
- } else if (!S.getCond()->EvaluateAsInt(Result, getContext())) {
+ else if (CPlusPlusWithProgress() ||
+ !S.getCond()->EvaluateAsInt(Result, getContext()))
LoopMustProgress = true;
- }
}
const SourceRange &R = S.getSourceRange();
@@ -994,7 +998,7 @@
S.getCond(), getProfileCount(S.getBody()), S.getBody());
if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
- if (C->isOne())
+ if (C->isOne() && CWithProgress())
FnIsMustProgress = false;
Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);
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