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R600/structurizer: improve inverting conditions

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Stop adding more instructions than necessary.

This is a candidate for the stable branch.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175349 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Christian Konig 2013-02-16 11:27:50 +00:00
parent 623977d9ba
commit ef6b24856d
1 changed files with 39 additions and 1 deletions
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40
lib/Target/R600/AMDGPUStructurizeCFG.cpp
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@ -22,8 +22,10 @@
#include "llvm/Analysis/RegionPass.h"
#include "llvm/IR/Module.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace llvm::PatternMatch;
namespace {
@ -193,6 +195,8 @@ class AMDGPUStructurizeCFG : public RegionPass {
void analyzeLoops(RegionNode *N);
Value *invert(Value *Condition);
Value *buildCondition(BranchInst *Term, unsigned Idx, bool Invert);
void gatherPredicates(RegionNode *N);
@ -305,6 +309,40 @@ void AMDGPUStructurizeCFG::analyzeLoops(RegionNode *N) {
}
}
/// \brief Invert the given condition
Value *AMDGPUStructurizeCFG::invert(Value *Condition) {
// First: Check if it's a constant
if (Condition == BoolTrue)
return BoolFalse;
if (Condition == BoolFalse)
return BoolTrue;
if (Condition == BoolUndef)
return BoolUndef;
// Second: If the condition is already inverted, return the original value
if (match(Condition, m_Not(m_Value(Condition))))
return Condition;
// Third: Check all the users for an invert
BasicBlock *Parent = cast<Instruction>(Condition)->getParent();
for (Value::use_iterator I = Condition->use_begin(),
E = Condition->use_end(); I != E; ++I) {
Instruction *User = dyn_cast<Instruction>(*I);
if (!User || User->getParent() != Parent)
continue;
if (match(*I, m_Not(m_Specific(Condition))))
return *I;
}
// Last option: Create a new instruction
return BinaryOperator::CreateNot(Condition, "", Parent->getTerminator());
}
/// \brief Build the condition for one edge
Value *AMDGPUStructurizeCFG::buildCondition(BranchInst *Term, unsigned Idx,
bool Invert) {
@ -313,7 +351,7 @@ Value *AMDGPUStructurizeCFG::buildCondition(BranchInst *Term, unsigned Idx,
Cond = Term->getCondition();
if (Idx != Invert)
Cond = BinaryOperator::CreateNot(Cond, "", Term);
Cond = invert(Cond);
}
return Cond;
}