diff options
| author | Evan Cheng <evan.cheng@apple.com> | 2012-02-28 06:42:03 +0000 |
|---|---|---|
| committer | Evan Cheng <evan.cheng@apple.com> | 2012-02-28 06:42:03 +0000 |
| commit | 87c7b09d8d7e7f04b720d298a7194c4473a8c524 (patch) | |
| tree | bbb0ebbd77e5a544fbe06f60bbb05802170d23d1 /llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | |
| parent | ccd651cac84b0620192f0ca404a841d52ad3a387 (diff) | |
| download | bcm5719-llvm-87c7b09d8d7e7f04b720d298a7194c4473a8c524.tar.gz bcm5719-llvm-87c7b09d8d7e7f04b720d298a7194c4473a8c524.zip | |
Some ARM implementaions, e.g. A-series, does return stack prediction. That is,
the processor keeps a return addresses stack (RAS) which stores the address
and the instruction execution state of the instruction after a function-call
type branch instruction.
Calling a "noreturn" function with normal call instructions (e.g. bl) can
corrupt RAS and causes 100% return misprediction so LLVM should use a
unconditional branch instead. i.e.
mov lr, pc
b _foo
The "mov lr, pc" is issued in order to get proper backtrace.
rdar://8979299
llvm-svn: 151623
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index fc8c531b5d9..796abf4a96c 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -3736,8 +3736,9 @@ SDValue SelectionDAG::getMemcpy(SDValue Chain, DebugLoc dl, SDValue Dst, std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(Chain, Type::getVoidTy(*getContext()), false, false, false, false, 0, - TLI.getLibcallCallingConv(RTLIB::MEMCPY), false, - /*isReturnValueUsed=*/false, + TLI.getLibcallCallingConv(RTLIB::MEMCPY), + /*isTailCall=*/false, + /*doesNotReturn=*/false, /*isReturnValueUsed=*/false, getExternalSymbol(TLI.getLibcallName(RTLIB::MEMCPY), TLI.getPointerTy()), Args, *this, dl); @@ -3788,8 +3789,9 @@ SDValue SelectionDAG::getMemmove(SDValue Chain, DebugLoc dl, SDValue Dst, std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(Chain, Type::getVoidTy(*getContext()), false, false, false, false, 0, - TLI.getLibcallCallingConv(RTLIB::MEMMOVE), false, - /*isReturnValueUsed=*/false, + TLI.getLibcallCallingConv(RTLIB::MEMMOVE), + /*isTailCall=*/false, + /*doesNotReturn=*/false, /*isReturnValueUsed=*/false, getExternalSymbol(TLI.getLibcallName(RTLIB::MEMMOVE), TLI.getPointerTy()), Args, *this, dl); @@ -3848,8 +3850,9 @@ SDValue SelectionDAG::getMemset(SDValue Chain, DebugLoc dl, SDValue Dst, std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(Chain, Type::getVoidTy(*getContext()), false, false, false, false, 0, - TLI.getLibcallCallingConv(RTLIB::MEMSET), false, - /*isReturnValueUsed=*/false, + TLI.getLibcallCallingConv(RTLIB::MEMSET), + /*isTailCall=*/false, + /*doesNotReturn*/false, /*isReturnValueUsed=*/false, getExternalSymbol(TLI.getLibcallName(RTLIB::MEMSET), TLI.getPointerTy()), Args, *this, dl); |
