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Improve static analysis of cold basic blocks 

Differential Revision: https://reviews.llvm.org/D52704

Reviewers: sebpop, tejohnson, brzycki, SirishP
Reviewed By: sebpop

llvm-svn: 343663
This commit is contained in:
Aditya Kumar 2018-10-03 06:21:05 +00:00
parent 9e20ade72a
commit a27014b851
1 changed files with 14 additions and 1 deletions
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15
llvm/lib/Transforms/IPO/HotColdSplitting.cpp
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@ -111,6 +111,18 @@ bool blockEndsInUnreachable(const BasicBlock &BB) {
return succ_empty(&BB);
}
static bool exceptionHandlingFunctions(const CallInst *CI) {
auto F = CI->getCalledFunction();
if (!F)
return false;
auto FName = F->getName();
return FName == "__cxa_begin_catch" ||
FName == "__cxa_free_exception" ||
FName == "__cxa_allocate_exception" ||
FName == "__cxa_begin_catch" ||
FName == "__cxa_end_catch";
}
static
bool unlikelyExecuted(const BasicBlock &BB) {
if (blockEndsInUnreachable(BB))
@ -122,7 +134,8 @@ bool unlikelyExecuted(const BasicBlock &BB) {
if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
// The block is cold if it calls functions tagged as cold or noreturn.
if (CI->hasFnAttr(Attribute::Cold) ||
CI->hasFnAttr(Attribute::NoReturn))
CI->hasFnAttr(Attribute::NoReturn) ||
exceptionHandlingFunctions(CI))
return true;
// Assume that inline assembly is hot code.