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This is part of https://reviews.llvm.org/D137381,
i've stumbled into this in
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=52989&q=label%3AProj-librawspeed
Look at the `callee_with_clang_attr()`.
`pure` attribute implies `nounwind`, and we successfully manifest that at IRgen,
and calls from nounwind functions treat it as non-unwinding,
except that when generating function definition,
we'd suddenly forget that it is nounwind...
Here, everything that could go wrong, goes wrong.
`CodeGenFunction::EmitStartEHSpec()` looks at the AST function exception
specification,
and not IR attributes, so
You'd think we can inferr the attribute in AST after the fact,
in `Sema::ActOnFunctionDeclarator()`, and while that is sufficient to get the
diagnostics,
the function exception specification has already been computed from parsed
attributes.
So we also need to adjust `handleFunctionTypeAttr()` (called by
`processTypeAttrs()`)
so it considers just-parsed `pure` as if it's `nothrow`...
It would somewhat less ugly if we could just infer `nothrow` attribute
during *attribute parsing* from `pure`/etc. Is that possible?
Also, OpenMP declare variant tests are showing an unexpected error,
looks like i'm missing some attribute propagation?
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D137901
Files:
clang/lib/CodeGen/CGCall.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/lib/Sema/SemaType.cpp
clang/test/CodeGenCXX/pr58798.cpp
clang/test/OpenMP/declare_variant_messages.cpp
clang/test/SemaCXX/attr-print.cpp
clang/test/SemaCXX/cxx11-attr-print.cpp
clang/test/SemaCXX/warn-throw-out-noexcept-func.cpp
Index: clang/test/SemaCXX/warn-throw-out-noexcept-func.cpp
===================================================================
--- clang/test/SemaCXX/warn-throw-out-noexcept-func.cpp
+++ clang/test/SemaCXX/warn-throw-out-noexcept-func.cpp
@@ -23,6 +23,9 @@
void __declspec(nothrow) SomeDeclspecThrow() {// expected-note {{function declared non-throwing here}}
throw 1; // expected-warning {{has a non-throwing exception specification but}}
}
+ void __attribute__((pure)) SomeAnotherThrow() {// expected-note {{function declared non-throwing here}}
+ throw 1; // expected-warning {{has a non-throwing exception specification but}}
+ }
};
struct M_ShouldNotDiag {
@@ -240,7 +243,7 @@
}
}
// As seen in p34973, this should not throw the warning. If there is an active
-// exception, catch(...) catches everything.
+// exception, catch(...) catches everything.
void o_ShouldNotDiag() noexcept {
try {
throw;
Index: clang/test/SemaCXX/cxx11-attr-print.cpp
===================================================================
--- clang/test/SemaCXX/cxx11-attr-print.cpp
+++ clang/test/SemaCXX/cxx11-attr-print.cpp
@@ -31,10 +31,10 @@
// CHECK: int c11_alignas _Alignas(alignof(int));
_Alignas(int) int c11_alignas;
-// CHECK: void foo() __attribute__((const));
+// CHECK: void foo() noexcept __attribute__((const));
void foo() __attribute__((const));
-// CHECK: void bar() __attribute__((__const));
+// CHECK: void bar() noexcept __attribute__((__const));
void bar() __attribute__((__const));
// FIXME: It's unfortunate that the string literal prints with the below three
@@ -65,8 +65,8 @@
// CHECK: int m __attribute__((aligned(4
// CHECK: int n alignas(4
-// CHECK: static int f() __attribute__((pure))
-// CHECK: static int g() {{\[}}[gnu::pure]]
+// CHECK: static int f() noexcept __attribute__((pure))
+// CHECK: static int g() noexcept {{\[}}[gnu::pure]]
template <typename T> struct S {
__attribute__((aligned(4))) int m;
alignas(4) int n;
@@ -80,8 +80,8 @@
// CHECK: int m __attribute__((aligned(4
// CHECK: int n alignas(4
-// CHECK: static int f() __attribute__((pure))
-// CHECK: static int g() {{\[}}[gnu::pure]]
+// CHECK: static int f() noexcept __attribute__((pure))
+// CHECK: static int g() noexcept {{\[}}[gnu::pure]]
template struct S<int>;
// CHECK: using Small2 {{\[}}[gnu::mode(byte)]] = int;
Index: clang/test/SemaCXX/attr-print.cpp
===================================================================
--- clang/test/SemaCXX/attr-print.cpp
+++ clang/test/SemaCXX/attr-print.cpp
@@ -7,14 +7,14 @@
// CHECK: int y __declspec(align(4));
__declspec(align(4)) int y;
-// CHECK: void foo() __attribute__((const));
+// CHECK: void foo() noexcept __attribute__((const));
void foo() __attribute__((const));
-// CHECK: void bar() __attribute__((__const));
+// CHECK: void bar() noexcept __attribute__((__const));
void bar() __attribute__((__const));
// FIXME: Print this with correct format.
-// CHECK: void foo1() __attribute__((noinline)) __attribute__((pure));
+// CHECK: void foo1() noexcept __attribute__((noinline)) __attribute__((pure));
void foo1() __attribute__((noinline, pure));
// CHECK: typedef int Small1 __attribute__((mode(byte)));
Index: clang/test/OpenMP/declare_variant_messages.cpp
===================================================================
--- clang/test/OpenMP/declare_variant_messages.cpp
+++ clang/test/OpenMP/declare_variant_messages.cpp
@@ -130,6 +130,7 @@
template <int C>
int score_and_cond_const_inst();
+// FIXME: why does this produce: error: exception specification in declaration does not match previous declaration
__attribute__((pure)) int pure() { return 0; }
#pragma omp declare variant(pure) match(user = {condition(1)}) // expected-warning {{ignoring return value of function declared with pure attribute}}
Index: clang/test/CodeGenCXX/pr58798.cpp
===================================================================
--- clang/test/CodeGenCXX/pr58798.cpp
+++ clang/test/CodeGenCXX/pr58798.cpp
@@ -14,7 +14,7 @@
// CHECK: Function Attrs: mustprogress noinline nounwind optnone willreturn memory(read)
// CHECK-LABEL: define {{[^@]+}}@_Z22callee_with_clang_attri
-// CHECK-SAME: (i32 noundef [[A:%.*]]) #[[ATTR0]] {
+// CHECK-SAME: (i32 noundef [[A:%.*]]) #[[ATTR0]] personality ptr @__gxx_personality_v0 {
// CHECK-NEXT: entry:
// CHECK-NEXT: [[A_ADDR:%.*]] = alloca i32, align 4
// CHECK-NEXT: store i32 [[A]], ptr [[A_ADDR]], align 4
@@ -24,10 +24,18 @@
// CHECK: if.then:
// CHECK-NEXT: [[EXCEPTION:%.*]] = call ptr @__cxa_allocate_exception(i64 4) #[[ATTR4:[0-9]+]]
// CHECK-NEXT: store i32 42, ptr [[EXCEPTION]], align 16
-// CHECK-NEXT: call void @__cxa_throw(ptr [[EXCEPTION]], ptr @_ZTIi, ptr null) #[[ATTR5:[0-9]+]]
-// CHECK-NEXT: unreachable
+// CHECK-NEXT: invoke void @__cxa_throw(ptr [[EXCEPTION]], ptr @_ZTIi, ptr null) #[[ATTR5:[0-9]+]]
+// CHECK-NEXT: to label [[UNREACHABLE:%.*]] unwind label [[TERMINATE_LPAD:%.*]]
// CHECK: if.end:
// CHECK-NEXT: ret i32 24
+// CHECK: terminate.lpad:
+// CHECK-NEXT: [[TMP1:%.*]] = landingpad { ptr, i32 }
+// CHECK-NEXT: catch ptr null
+// CHECK-NEXT: [[TMP2:%.*]] = extractvalue { ptr, i32 } [[TMP1]], 0
+// CHECK-NEXT: call void @__clang_call_terminate(ptr [[TMP2]]) #[[ATTR6:[0-9]+]]
+// CHECK-NEXT: unreachable
+// CHECK: unreachable:
+// CHECK-NEXT: unreachable
//
// CHECK: Function Attrs: mustprogress noinline nounwind optnone
@@ -72,7 +80,7 @@
// CHECK-NEXT: [[TMP1:%.*]] = landingpad { ptr, i32 }
// CHECK-NEXT: catch ptr null
// CHECK-NEXT: [[TMP2:%.*]] = extractvalue { ptr, i32 } [[TMP1]], 0
-// CHECK-NEXT: call void @__clang_call_terminate(ptr [[TMP2]]) #[[ATTR6:[0-9]+]]
+// CHECK-NEXT: call void @__clang_call_terminate(ptr [[TMP2]]) #[[ATTR6]]
// CHECK-NEXT: unreachable
// CHECK: unreachable:
// CHECK-NEXT: unreachable
@@ -89,7 +97,6 @@
// CHECK-NEXT: ret i32 [[CALL]]
//
-
// Forward declarations:
__attribute__((pure)) int callee_with_clang_attr(int a);
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -7771,7 +7771,10 @@
return true;
}
- if (attr.getKind() == ParsedAttr::AT_NoThrow) {
+ if (attr.getKind() == ParsedAttr::AT_NoThrow ||
+ attr.getKind() == ParsedAttr::AT_Pure ||
+ attr.getKind() == ParsedAttr::AT_Const ||
+ attr.getKind() == ParsedAttr::AT_NoAlias) {
// Delay if this is not a function type.
if (!unwrapped.isFunctionType())
return false;
@@ -8522,8 +8525,11 @@
break;
case ParsedAttr::AT_NoThrow:
- // Exception Specifications aren't generally supported in C mode throughout
- // clang, so revert to attribute-based handling for C.
+ case ParsedAttr::AT_Pure: // (implies nothrow attr)
+ case ParsedAttr::AT_Const: // (implies nothrow attr)
+ case ParsedAttr::AT_NoAlias: // (implies nothrow attr)
+ // Exception Specifications aren't generally supported in C mode
+ // throughout clang, so revert to attribute-based handling for C.
if (!state.getSema().getLangOpts().CPlusPlus)
break;
[[fallthrough]];
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -8790,6 +8790,27 @@
if (!AL.isUsedAsTypeAttr())
handleSimpleAttribute<NoThrowAttr>(S, D, AL);
break;
+ case ParsedAttr::AT_Pure:
+ handleSimpleAttribute<PureAttr>(S, D, AL);
+ if (!D->hasAttr<NoThrowAttr>()) {
+ handleSimpleAttribute<NoThrowAttr>(S, D, AL);
+ D->getAttr<NoThrowAttr>()->setImplicit(true);
+ }
+ break;
+ case ParsedAttr::AT_Const:
+ handleSimpleAttribute<ConstAttr>(S, D, AL);
+ if (!D->hasAttr<NoThrowAttr>()) {
+ handleSimpleAttribute<NoThrowAttr>(S, D, AL);
+ D->getAttr<NoThrowAttr>()->setImplicit(true);
+ }
+ break;
+ case ParsedAttr::AT_NoAlias:
+ handleSimpleAttribute<NoAliasAttr>(S, D, AL);
+ if (!D->hasAttr<NoThrowAttr>()) {
+ handleSimpleAttribute<NoThrowAttr>(S, D, AL);
+ D->getAttr<NoThrowAttr>()->setImplicit(true);
+ }
+ break;
case ParsedAttr::AT_CUDAShared:
handleSharedAttr(S, D, AL);
break;
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -2174,21 +2174,19 @@
FuncAttrs.addAttribute(llvm::Attribute::NoMerge);
}
- // 'const', 'pure' and 'noalias' attributed functions are also nounwind.
+ // 'const', 'pure' and 'noalias' attributed functions are also nounwind,
+ // but that is manifested in AST, so we don't need to deal with that here.
if (TargetDecl->hasAttr<ConstAttr>()) {
FuncAttrs.addMemoryAttr(llvm::MemoryEffects::none());
- FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
// gcc specifies that 'const' functions have greater restrictions than
// 'pure' functions, so they also cannot have infinite loops.
FuncAttrs.addAttribute(llvm::Attribute::WillReturn);
} else if (TargetDecl->hasAttr<PureAttr>()) {
FuncAttrs.addMemoryAttr(llvm::MemoryEffects::readOnly());
- FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
// gcc specifies that 'pure' functions cannot have infinite loops.
FuncAttrs.addAttribute(llvm::Attribute::WillReturn);
} else if (TargetDecl->hasAttr<NoAliasAttr>()) {
FuncAttrs.addMemoryAttr(llvm::MemoryEffects::argMemOnly());
- FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
}
if (TargetDecl->hasAttr<RestrictAttr>())
RetAttrs.addAttribute(llvm::Attribute::NoAlias);
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