6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-08 03:30:22 +00:00
Code Issues Projects Releases Wiki Activity

Revert "[GVN] Perform Scalar PRE on gep indices that feed loads before doing Load PRE."

Browse Source 
This reverts commit r221924.  It appears the commit was a bit premature and is causing
bot failures that need further investigation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221939 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chad Rosier 2014-11-13 22:54:59 +00:00
parent a5408b9c7c
commit 7984fde2dc
2 changed files with 170 additions and 219 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

74
lib/Transforms/Scalar/GVN.cpp
View File

@ -20,7 +20,6 @@
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
@ -710,7 +709,6 @@ namespace {
void dump(DenseMap<uint32_t, Value*> &d);
bool iterateOnFunction(Function &F);
bool performPRE(Function &F);
bool performScalarPRE(Instruction *I);
Value *findLeader(const BasicBlock *BB, uint32_t num);
void cleanupGlobalSets();
void verifyRemoved(const Instruction *I) const;
@ -1731,14 +1729,6 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
return false;
}
// If this load follows a GEP, see if we can PRE the indices before analyzing.
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0))) {
for(GetElementPtrInst::op_iterator OI = GEP->idx_begin(),
OE = GEP->idx_end(); OI != OE; ++OI)
if (Instruction *I = dyn_cast<Instruction>(OI->get()))
performScalarPRE(I);
}
// Step 2: Analyze the availability of the load
AvailValInBlkVect ValuesPerBlock;
UnavailBlkVect UnavailableBlocks;
@ -2441,27 +2431,40 @@ bool GVN::processBlock(BasicBlock *BB) {
return ChangedFunction;
}
bool GVN::performScalarPRE(Instruction *CurInst) {
/// performPRE - Perform a purely local form of PRE that looks for diamond
/// control flow patterns and attempts to perform simple PRE at the join point.
bool GVN::performPRE(Function &F) {
bool Changed = false;
SmallVector<std::pair<Value*, BasicBlock*>, 8> predMap;
for (BasicBlock *CurrentBlock : depth_first(&F.getEntryBlock())) {
// Nothing to PRE in the entry block.
if (CurrentBlock == &F.getEntryBlock()) continue;
// Don't perform PRE on a landing pad.
if (CurrentBlock->isLandingPad()) continue;
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
Instruction *CurInst = BI++;
if (isa<AllocaInst>(CurInst) ||
isa<TerminatorInst>(CurInst) || isa<PHINode>(CurInst) ||
CurInst->getType()->isVoidTy() ||
CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
isa<DbgInfoIntrinsic>(CurInst))
return false;
continue;
// Don't do PRE on compares. The PHI would prevent CodeGenPrepare from
// sinking the compare again, and it would force the code generator to
// move the i1 from processor flags or predicate registers into a general
// purpose register.
if (isa<CmpInst>(CurInst))
return false;
continue;
// We don't currently value number ANY inline asm calls.
if (CallInst *CallI = dyn_cast<CallInst>(CurInst))
if (CallI->isInlineAsm())
return false;
continue;
uint32_t ValNo = VN.lookup(CurInst);
@ -2474,7 +2477,6 @@ bool GVN::performScalarPRE(Instruction *CurInst) {
unsigned NumWith = 0;
unsigned NumWithout = 0;
BasicBlock *PREPred = nullptr;
BasicBlock *CurrentBlock = CurInst->getParent();
predMap.clear();
for (pred_iterator PI = pred_begin(CurrentBlock),
@ -2509,11 +2511,11 @@ bool GVN::performScalarPRE(Instruction *CurInst) {
// Don't do PRE when it might increase code size, i.e. when
// we would need to insert instructions in more than one pred.
if (NumWithout != 1 || NumWith == 0)
return false;
continue;
// Don't do PRE across indirect branch.
if (isa<IndirectBrInst>(PREPred->getTerminator()))
return false;
continue;
// We can't do PRE safely on a critical edge, so instead we schedule
// the edge to be split and perform the PRE the next time we iterate
@ -2521,7 +2523,7 @@ bool GVN::performScalarPRE(Instruction *CurInst) {
unsigned SuccNum = GetSuccessorNumber(PREPred, CurrentBlock);
if (isCriticalEdge(PREPred->getTerminator(), SuccNum)) {
toSplit.push_back(std::make_pair(PREPred->getTerminator(), SuccNum));
return false;
continue;
}
// Instantiate the expression in the predecessor that lacked it.
@ -2550,7 +2552,7 @@ bool GVN::performScalarPRE(Instruction *CurInst) {
if (!success) {
DEBUG(verifyRemoved(PREInstr));
delete PREInstr;
return false;
continue;
}
PREInstr->insertBefore(PREPred->getTerminator());
@ -2597,24 +2599,7 @@ bool GVN::performScalarPRE(Instruction *CurInst) {
if (MD) MD->removeInstruction(CurInst);
DEBUG(verifyRemoved(CurInst));
CurInst->eraseFromParent();
return true;
}
/// performPRE - Perform a purely local form of PRE that looks for diamond
/// control flow patterns and attempts to perform simple PRE at the join point.
bool GVN::performPRE(Function &F) {
bool Changed = false;
for (BasicBlock *CurrentBlock : depth_first(&F.getEntryBlock())) {
// Nothing to PRE in the entry block.
if (CurrentBlock == &F.getEntryBlock()) continue;
// Don't perform PRE on a landing pad.
if (CurrentBlock->isLandingPad()) continue;
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
Instruction *CurInst = BI++;
Changed = performScalarPRE(CurInst);
Changed = true;
}
}
@ -2652,11 +2637,26 @@ bool GVN::iterateOnFunction(Function &F) {
// Top-down walk of the dominator tree
bool Changed = false;
#if 0
// Needed for value numbering with phi construction to work.
ReversePostOrderTraversal<Function*> RPOT(&F);
for (ReversePostOrderTraversal<Function*>::rpo_iterator RI = RPOT.begin(),
RE = RPOT.end(); RI != RE; ++RI)
Changed |= processBlock(*RI);
#else
// Save the blocks this function have before transformation begins. GVN may
// split critical edge, and hence may invalidate the RPO/DT iterator.
//
std::vector<BasicBlock *> BBVect;
BBVect.reserve(256);
for (DomTreeNode *X : depth_first(DT->getRootNode()))
BBVect.push_back(X->getBlock());
for (std::vector<BasicBlock *>::iterator I = BBVect.begin(), E = BBVect.end();
I != E; I++)
Changed |= processBlock(*I);
#endif
return Changed;
}

49
test/Transforms/GVN/pre-gep-load.ll
View File

@ -1,49 +0,0 @@
; RUN: opt < %s -basicaa -gvn -enable-load-pre -S | FileCheck %s
target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
target triple = "aarch64--linux-gnu"
define double @foo(i32 %stat, i32 %i, double** %p) {
; CHECK-LABEL: @foo(
entry:
switch i32 %stat, label %sw.default [
i32 0, label %sw.bb
i32 1, label %sw.bb
i32 2, label %sw.bb2
]
sw.bb: ; preds = %entry, %entry
%idxprom = sext i32 %i to i64
%arrayidx = getelementptr inbounds double** %p, i64 0
%0 = load double** %arrayidx, align 8
%arrayidx1 = getelementptr inbounds double* %0, i64 %idxprom
%1 = load double* %arrayidx1, align 8
%sub = fsub double %1, 1.000000e+00
%cmp = fcmp olt double %sub, 0.000000e+00
br i1 %cmp, label %if.then, label %if.end
if.then: ; preds = %sw.bb
br label %return
if.end: ; preds = %sw.bb
br label %sw.bb2
sw.bb2: ; preds = %if.end, %entry
%idxprom3 = sext i32 %i to i64
%arrayidx4 = getelementptr inbounds double** %p, i64 0
%2 = load double** %arrayidx4, align 8
%arrayidx5 = getelementptr inbounds double* %2, i64 %idxprom3
%3 = load double* %arrayidx5, align 8
; CHECK: sw.bb2:
; CHECK-NEXT-NOT: sext
; CHECK-NEXT: phi double [
; CHECK-NOT: load
%sub6 = fsub double 3.000000e+00, %3
br label %return
sw.default: ; preds = %entry
br label %return
return: ; preds = %sw.default, %sw.bb2, %if.then
%retval.0 = phi double [ 0.000000e+00, %sw.default ], [ %sub6, %sw.bb2 ], [ %sub, %if.then ]
ret double %retval.0
}