6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-19 06:31:18 +00:00
Code Issues Projects Releases Wiki Activity

Lift a cheap early exit test above loops and other complex early exit

Browse Source 
tests. No need to pay the high cost when we're never going to do
anything.

No functionality changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173331 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2013-01-24 08:22:40 +00:00
parent c61bc7a90c
commit 9e62095261
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -1370,6 +1370,11 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
/// ///
/// \returns true if the conditional block is removed. /// \returns true if the conditional block is removed.
static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) { static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) {
// Be conservative for now. FP select instruction can often be expensive.
Value *BrCond = BI->getCondition();
if (isa<FCmpInst>(BrCond))
return false;
// Only speculatively execution a single instruction (not counting the // Only speculatively execution a single instruction (not counting the
// terminator) for now. // terminator) for now.
Instruction *HInst = NULL; Instruction *HInst = NULL;
@ -1409,11 +1414,6 @@ static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) {
} }
} }
// Be conservative for now. FP select instruction can often be expensive.
Value *BrCond = BI->getCondition();
if (isa<FCmpInst>(BrCond))
return false;
// If BB1 is actually on the false edge of the conditional branch, remember // If BB1 is actually on the false edge of the conditional branch, remember
// to swap the select operands later. // to swap the select operands later.
bool Invert = false; bool Invert = false;