Author: hans
Date: Tue Feb 12 00:35:38 2019
New Revision: 353807
URL: http://llvm.org/viewvc/llvm-project?rev=353807&view=rev
Log:
Merging r353495:
------------------------------------------------------------------------
r353495 | jfb | 2019-02-08 02:29:17 +0100 (Fri, 08 Feb 2019) | 32 lines
Variable auto-init: fix __block initialization
Summary:
Automatic initialization [1] of __block variables was trampling over the block's
headers after they'd been initialized, which caused self-init usage to crash,
such as here:
typedef struct XYZ { void (^block)(); } *xyz_t;
__attribute__((noinline))
xyz_t create(void (^block)()) {
xyz_t myself = malloc(sizeof(struct XYZ));
myself->block = block;
return myself;
}
int main() {
__block xyz_t captured = create(^(){ (void)captured; });
}
This type of code shouldn't be broken by variable auto-init, even if it's
sketchy.
[1] With -ftrivial-auto-var-init=pattern
<rdar://problem/47798396>
Reviewers: rjmccall, pcc, kcc
Subscribers: jkorous, dexonsmith, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D57797
------------------------------------------------------------------------
Modified:
cfe/branches/release_80/ (props changed)
cfe/branches/release_80/lib/CodeGen/CGDecl.cpp
cfe/branches/release_80/test/CodeGenCXX/trivial-auto-var-init.cpp
Propchange: cfe/branches/release_80/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Tue Feb 12 00:35:38 2019
@@ -1,4 +1,4 @@
/cfe/branches/type-system-rewrite:134693-134817
-/cfe/trunk:351334,351340,351344,351360,351457,351459,351531,351579-351580,352040,352079,352099,352102,352105,352156,352221-352222,352229,352307,352323,352463,352539,352610,352672,352822,353393
+/cfe/trunk:351334,351340,351344,351360,351457,351459,351531,351579-351580,352040,352079,352099,352102,352105,352156,352221-352222,352229,352307,352323,352463,352539,352610,352672,352822,353393,353495
/cfe/trunk/test:170344
/cfe/trunk/test/SemaTemplate:126920
Modified: cfe/branches/release_80/lib/CodeGen/CGDecl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/branches/release_80/lib/CodeGen/CGDecl.cpp?rev=353807&r1=353806&r2=353807&view=diff
==============================================================================
--- cfe/branches/release_80/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/branches/release_80/lib/CodeGen/CGDecl.cpp Tue Feb 12 00:35:38 2019
@@ -1631,11 +1631,15 @@ void CodeGenFunction::EmitAutoVarInit(co
? LangOptions::TrivialAutoVarInitKind::Uninitialized
: getContext().getLangOpts().getTrivialAutoVarInit()));
- auto initializeWhatIsTechnicallyUninitialized = [&]() {
+ auto initializeWhatIsTechnicallyUninitialized = [&](Address Loc) {
if (trivialAutoVarInit ==
LangOptions::TrivialAutoVarInitKind::Uninitialized)
return;
+ // Only initialize a __block's storage: we always initialize the header.
+ if (emission.IsEscapingByRef)
+ Loc = emitBlockByrefAddress(Loc, &D, /*follow=*/false);
+
CharUnits Size = getContext().getTypeSizeInChars(type);
if (!Size.isZero()) {
switch (trivialAutoVarInit) {
@@ -1713,7 +1717,7 @@ void CodeGenFunction::EmitAutoVarInit(co
};
if (isTrivialInitializer(Init)) {
- initializeWhatIsTechnicallyUninitialized();
+ initializeWhatIsTechnicallyUninitialized(Loc);
return;
}
@@ -1727,7 +1731,7 @@ void CodeGenFunction::EmitAutoVarInit(co
}
if (!constant) {
- initializeWhatIsTechnicallyUninitialized();
+ initializeWhatIsTechnicallyUninitialized(Loc);
LValue lv = MakeAddrLValue(Loc, type);
lv.setNonGC(true);
return EmitExprAsInit(Init, &D, lv, capturedByInit);
Modified: cfe/branches/release_80/test/CodeGenCXX/trivial-auto-var-init.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/branches/release_80/test/CodeGenCXX/trivial-auto-var-init.cpp?rev=353807&r1=353806&r2=353807&view=diff
==============================================================================
--- cfe/branches/release_80/test/CodeGenCXX/trivial-auto-var-init.cpp (original)
+++ cfe/branches/release_80/test/CodeGenCXX/trivial-auto-var-init.cpp Tue Feb
12 00:35:38 2019
@@ -30,6 +30,32 @@ void test_block() {
used(block);
}
+// Using the variable being initialized is typically UB in C, but for blocks we
+// can be nice: they imply extra book-keeping and we can do the auto-init
before
+// any of said book-keeping.
+//
+// UNINIT-LABEL: test_block_self_init(
+// ZERO-LABEL: test_block_self_init(
+// ZERO: %block = alloca <{ i8*, i32, i32, i8*,
%struct.__block_descriptor*, i8* }>, align 8
+// ZERO: %captured1 = getelementptr inbounds
%struct.__block_byref_captured, %struct.__block_byref_captured* %captured, i32
0, i32 4
+// ZERO-NEXT: store %struct.XYZ* null, %struct.XYZ** %captured1, align 8
+// ZERO: %call = call %struct.XYZ* @create(
+// PATTERN-LABEL: test_block_self_init(
+// PATTERN: %block = alloca <{ i8*, i32, i32, i8*,
%struct.__block_descriptor*, i8* }>, align 8
+// PATTERN: %captured1 = getelementptr inbounds
%struct.__block_byref_captured, %struct.__block_byref_captured* %captured, i32
0, i32 4
+// PATTERN-NEXT: store %struct.XYZ* inttoptr (i64 -6148914691236517206 to
%struct.XYZ*), %struct.XYZ** %captured1, align 8
+// PATTERN: %call = call %struct.XYZ* @create(
+void test_block_self_init() {
+ using Block = void (^)();
+ typedef struct XYZ {
+ Block block;
+ } * xyz_t;
+ extern xyz_t create(Block block);
+ __block xyz_t captured = create(^() {
+ (void)captured;
+ });
+}
+
// This type of code is currently not handled by zero / pattern initialization.
// The test will break when that is fixed.
// UNINIT-LABEL: test_goto_unreachable_value(
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