mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-13 04:30:23 +00:00
Add a prototype of a new peephole optimizing pass that uses LazyValue info to simplify PHIs and select's.
This pass addresses the missed optimizations from PR2581 and PR4420. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112325 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
ee61fcf98b
commit
a0b59f6bd2
@ -149,6 +149,7 @@ namespace {
|
||||
(void) llvm::createLintPass();
|
||||
(void) llvm::createSinkingPass();
|
||||
(void) llvm::createLowerAtomicPass();
|
||||
(void) llvm::createValuePropagationPass();
|
||||
|
||||
(void)new llvm::IntervalPartition();
|
||||
(void)new llvm::FindUsedTypes();
|
||||
|
@ -343,6 +343,12 @@ FunctionPass *createSinkingPass();
|
||||
//
|
||||
Pass *createLowerAtomicPass();
|
||||
|
||||
//===----------------------------------------------------------------------===//
|
||||
//
|
||||
// ValuePropagation - Propagate CFG-derived value information
|
||||
//
|
||||
Pass *createValuePropagationPass();
|
||||
|
||||
} // End llvm namespace
|
||||
|
||||
#endif
|
||||
|
113
lib/Transforms/Scalar/ValuePropagation.cpp
Normal file
113
lib/Transforms/Scalar/ValuePropagation.cpp
Normal file
@ -0,0 +1,113 @@
|
||||
//===- ValuePropagation.cpp - Propagate information derived control flow --===//
|
||||
//
|
||||
// The LLVM Compiler Infrastructure
|
||||
//
|
||||
// This file is distributed under the University of Illinois Open Source
|
||||
// License. See LICENSE.TXT for details.
|
||||
//
|
||||
//===----------------------------------------------------------------------===//
|
||||
//
|
||||
// This file implements the Value Propagation pass.
|
||||
//
|
||||
//===----------------------------------------------------------------------===//
|
||||
|
||||
#define DEBUG_TYPE "value-propagation"
|
||||
#include "llvm/Transforms/Scalar.h"
|
||||
#include "llvm/Function.h"
|
||||
#include "llvm/Instructions.h"
|
||||
#include "llvm/Pass.h"
|
||||
#include "llvm/Analysis/LazyValueInfo.h"
|
||||
#include "llvm/Transforms/Utils/Local.h"
|
||||
using namespace llvm;
|
||||
|
||||
namespace {
|
||||
class ValuePropagation : public FunctionPass {
|
||||
LazyValueInfo *LVI;
|
||||
|
||||
bool processSelect(SelectInst *SI);
|
||||
bool processPHI(PHINode *P);
|
||||
|
||||
public:
|
||||
static char ID;
|
||||
ValuePropagation(): FunctionPass(ID) { }
|
||||
|
||||
bool runOnFunction(Function &F);
|
||||
|
||||
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||
AU.addRequired<LazyValueInfo>();
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
char ValuePropagation::ID = 0;
|
||||
INITIALIZE_PASS(ValuePropagation, "value-propagation",
|
||||
"Value Propagation", false, false);
|
||||
|
||||
// Public interface to the Value Propagation pass
|
||||
Pass *llvm::createValuePropagationPass() {
|
||||
return new ValuePropagation();
|
||||
}
|
||||
|
||||
bool ValuePropagation::processSelect(SelectInst *S) {
|
||||
Constant *C = LVI->getConstant(S->getOperand(0), S->getParent());
|
||||
if (!C) return false;
|
||||
|
||||
ConstantInt *CI = dyn_cast<ConstantInt>(C);
|
||||
if (!CI) return false;
|
||||
|
||||
if (CI->isZero()) {
|
||||
S->replaceAllUsesWith(S->getOperand(2));
|
||||
S->eraseFromParent();
|
||||
} else if (CI->isOne()) {
|
||||
S->replaceAllUsesWith(S->getOperand(1));
|
||||
S->eraseFromParent();
|
||||
} else {
|
||||
assert(0 && "Select on constant is neither 0 nor 1?");
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
bool ValuePropagation::processPHI(PHINode *P) {
|
||||
bool changed = false;
|
||||
|
||||
BasicBlock *BB = P->getParent();
|
||||
for (unsigned i = 0; i < P->getNumIncomingValues(); ++i) {
|
||||
Constant *C = LVI->getConstantOnEdge(P->getIncomingValue(i),
|
||||
P->getIncomingBlock(i),
|
||||
BB);
|
||||
if (!C || C == P->getIncomingValue(i)) continue;
|
||||
|
||||
P->setIncomingValue(i, C);
|
||||
changed = true;
|
||||
}
|
||||
|
||||
if (Value *ConstVal = P->hasConstantValue()) {
|
||||
P->replaceAllUsesWith(ConstVal);
|
||||
P->eraseFromParent();
|
||||
changed = true;
|
||||
}
|
||||
|
||||
return changed;
|
||||
}
|
||||
|
||||
bool ValuePropagation::runOnFunction(Function &F) {
|
||||
LVI = &getAnalysis<LazyValueInfo>();
|
||||
|
||||
bool changed = false;
|
||||
|
||||
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
|
||||
for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ) {
|
||||
Instruction *II = BI++;
|
||||
if (SelectInst *SI = dyn_cast<SelectInst>(II))
|
||||
changed |= processSelect(SI);
|
||||
else if (PHINode *P = dyn_cast<PHINode>(II))
|
||||
changed |= processPHI(P);
|
||||
}
|
||||
|
||||
if (changed)
|
||||
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
|
||||
SimplifyInstructionsInBlock(FI);
|
||||
|
||||
return changed;
|
||||
}
|
3
test/Transforms/ValuePropagation/dg.exp
Normal file
3
test/Transforms/ValuePropagation/dg.exp
Normal file
@ -0,0 +1,3 @@
|
||||
load_lib llvm.exp
|
||||
|
||||
RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.ll]]
|
17
test/Transforms/ValuePropagation/phi.ll
Normal file
17
test/Transforms/ValuePropagation/phi.ll
Normal file
@ -0,0 +1,17 @@
|
||||
; RUN: opt < %s -value-propagation -S | FileCheck %s
|
||||
; PR2581
|
||||
|
||||
; CHECK: @run
|
||||
define i32 @run(i1 %C) nounwind {
|
||||
br i1 %C, label %exit, label %body
|
||||
|
||||
body: ; preds = %0
|
||||
; CHECK-NOT: select
|
||||
%A = select i1 %C, i32 10, i32 11 ; <i32> [#uses=1]
|
||||
; CHECK: ret i32 11
|
||||
ret i32 %A
|
||||
|
||||
exit: ; preds = %0
|
||||
; CHECK: ret i32 10
|
||||
ret i32 10
|
||||
}
|
25
test/Transforms/ValuePropagation/select.ll
Normal file
25
test/Transforms/ValuePropagation/select.ll
Normal file
@ -0,0 +1,25 @@
|
||||
; RUN: opt < %s -value-propagation -S | FileCheck %s
|
||||
; PR4420
|
||||
|
||||
declare i1 @ext()
|
||||
; CHECK: @foo
|
||||
define i1 @foo() {
|
||||
entry:
|
||||
%cond = tail call i1 @ext() ; <i1> [#uses=2]
|
||||
br i1 %cond, label %bb1, label %bb2
|
||||
|
||||
bb1: ; preds = %entry
|
||||
%cond2 = tail call i1 @ext() ; <i1> [#uses=1]
|
||||
br i1 %cond2, label %bb3, label %bb2
|
||||
|
||||
bb2: ; preds = %bb1, %entry
|
||||
; CHECK-NOT: phi i1
|
||||
%cond_merge = phi i1 [ %cond, %entry ], [ false, %bb1 ] ; <i1> [#uses=1]
|
||||
; CHECK: ret i1 false
|
||||
ret i1 %cond_merge
|
||||
|
||||
bb3: ; preds = %bb1
|
||||
%res = tail call i1 @ext() ; <i1> [#uses=1]
|
||||
; CHECK: ret i1 %res
|
||||
ret i1 %res
|
||||
}
|
Loading…
Reference in New Issue
Block a user