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authorTim Northover <tnorthover@apple.com>2014-06-13 14:24:07 +0000
committerTim Northover <tnorthover@apple.com>2014-06-13 14:24:07 +0000
commit8f2a85e0995a5bb2943bf9c5021950beaf48265e (patch)
tree4cb75b9eb20ea78ff6c905e4995176e68eccb937 /lib/AsmParser
parent1d5e37946d2ec6ca7834e333a850276569593a90 (diff)
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IR: add "cmpxchg weak" variant to support permitted failure.
This commit adds a weak variant of the cmpxchg operation, as described in C++11. A cmpxchg instruction with this modifier is permitted to fail to store, even if the comparison indicated it should. As a result, cmpxchg instructions must return a flag indicating success in addition to their original iN value loaded. Thus, for uniformity *all* cmpxchg instructions now return "{ iN, i1 }". The second flag is 1 when the store succeeded. At the DAG level, a new ATOMIC_CMP_SWAP_WITH_SUCCESS node has been added as the natural representation for the new cmpxchg instructions. It is a strong cmpxchg. By default this gets Expanded to the existing ATOMIC_CMP_SWAP during Legalization, so existing backends should see no change in behaviour. If they wish to deal with the enhanced node instead, they can call setOperationAction on it. Beware: as a node with 2 results, it cannot be selected from TableGen. Currently, no use is made of the extra information provided in this patch. Test updates are almost entirely adapting the input IR to the new scheme. Summary for out of tree users: ------------------------------ + Legacy Bitcode files are upgraded during read. + Legacy assembly IR files will be invalid. + Front-ends must adapt to different type for "cmpxchg". + Backends should be unaffected by default. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210903 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/AsmParser')
-rw-r--r--lib/AsmParser/LLLexer.cpp2
-rw-r--r--lib/AsmParser/LLParser.cpp13
-rw-r--r--lib/AsmParser/LLToken.h3
3 files changed, 12 insertions, 6 deletions
diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index b9193e89e7..1334825a7d 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -490,7 +490,7 @@ lltok::Kind LLLexer::LexIdentifier() {
KEYWORD(available_externally);
KEYWORD(linkonce);
KEYWORD(linkonce_odr);
- KEYWORD(weak);
+ KEYWORD(weak); // Use as a linkage, and a modifier for "cmpxchg".
KEYWORD(weak_odr);
KEYWORD(appending);
KEYWORD(dllimport);
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index a528a7e7a5..0c188f983f 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -4256,8 +4256,8 @@ int LLParser::ParseStore(Instruction *&Inst, PerFunctionState &PFS) {
}
/// ParseCmpXchg
-/// ::= 'cmpxchg' 'volatile'? TypeAndValue ',' TypeAndValue ',' TypeAndValue
-/// 'singlethread'? AtomicOrdering AtomicOrdering
+/// ::= 'cmpxchg' 'weak'? 'volatile'? TypeAndValue ',' TypeAndValue ','
+/// TypeAndValue 'singlethread'? AtomicOrdering AtomicOrdering
int LLParser::ParseCmpXchg(Instruction *&Inst, PerFunctionState &PFS) {
Value *Ptr, *Cmp, *New; LocTy PtrLoc, CmpLoc, NewLoc;
bool AteExtraComma = false;
@@ -4265,6 +4265,10 @@ int LLParser::ParseCmpXchg(Instruction *&Inst, PerFunctionState &PFS) {
AtomicOrdering FailureOrdering = NotAtomic;
SynchronizationScope Scope = CrossThread;
bool isVolatile = false;
+ bool isWeak = false;
+
+ if (EatIfPresent(lltok::kw_weak))
+ isWeak = true;
if (EatIfPresent(lltok::kw_volatile))
isVolatile = true;
@@ -4297,9 +4301,10 @@ int LLParser::ParseCmpXchg(Instruction *&Inst, PerFunctionState &PFS) {
return Error(NewLoc, "cmpxchg operand must be power-of-two byte-sized"
" integer");
- AtomicCmpXchgInst *CXI = new AtomicCmpXchgInst(Ptr, Cmp, New, SuccessOrdering,
- FailureOrdering, Scope);
+ AtomicCmpXchgInst *CXI = new AtomicCmpXchgInst(
+ Ptr, Cmp, New, SuccessOrdering, FailureOrdering, Scope);
CXI->setVolatile(isVolatile);
+ CXI->setWeak(isWeak);
Inst = CXI;
return AteExtraComma ? InstExtraComma : InstNormal;
}
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index 3ce09503f5..af8b0da78b 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -42,7 +42,8 @@ namespace lltok {
kw_linker_private, // NOTE: deprecated, for parser compatibility
kw_linker_private_weak, // NOTE: deprecated, for parser compatibility
kw_linkonce, kw_linkonce_odr,
- kw_weak, kw_weak_odr, kw_appending,
+ kw_weak, // Used as a linkage, and a modifier for "cmpxchg".
+ kw_weak_odr, kw_appending,
kw_dllimport, kw_dllexport, kw_common, kw_available_externally,
kw_default, kw_hidden, kw_protected,
kw_unnamed_addr,