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author | Chris Lattner <sabre@nondot.org> | 2009-11-28 16:08:18 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2009-11-28 16:08:18 +0000 |
commit | 0c264b16b0e8a373888d1a5cfeb90af4fda3cd14 (patch) | |
tree | 2d127a4a10abe1670f5066b3c3eb69e26f732996 /lib | |
parent | dd696052f0e4ecc973d105be19cf1b4b72f9a0c4 (diff) | |
download | llvm-0c264b16b0e8a373888d1a5cfeb90af4fda3cd14.tar.gz llvm-0c264b16b0e8a373888d1a5cfeb90af4fda3cd14.tar.bz2 llvm-0c264b16b0e8a373888d1a5cfeb90af4fda3cd14.tar.xz |
reenable load address insertion in load pre. This allows us to
handle cases like this:
void test(int N, double* G) {
long j;
for (j = 1; j < N - 1; j++)
G[j+1] = G[j] + G[j+1];
}
where G[1] isn't live into the loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90041 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index 6311491c7d..6f1c32c004 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -1438,16 +1438,19 @@ bool GVN::processNonLocalLoad(LoadInst *LI, // FIXME: This may insert a computation, but we don't tell scalar GVN // optimization stuff about it. How do we do this? SmallVector<Instruction*, 8> NewInsts; -#if 0 - Value *LoadPtr = - MD->InsertPHITranslatedPointer(LI->getOperand(0), LoadBB, - UnavailablePred, TD, *DT, NewInsts); -#else - Value *LoadPtr = - MD->GetAvailablePHITranslatedValue(LI->getOperand(0), LoadBB, - UnavailablePred, TD, *DT); -#endif + Value *LoadPtr = 0; + // If all preds have a single successor, then we know it is safe to insert the + // load on the pred (?!?), so we can insert code to materialize the pointer if + // it is not available. + if (allSingleSucc) { + LoadPtr = MD->InsertPHITranslatedPointer(LI->getOperand(0), LoadBB, + UnavailablePred, TD, *DT,NewInsts); + } else { + LoadPtr = MD->GetAvailablePHITranslatedValue(LI->getOperand(0), LoadBB, + UnavailablePred, TD, *DT); + } + // If we couldn't find or insert a computation of this phi translated value, // we fail PRE. if (LoadPtr == 0) { @@ -1467,14 +1470,19 @@ bool GVN::processNonLocalLoad(LoadInst *LI, // put anywhere; this can be improved, but should be conservatively safe. if (!allSingleSucc && // FIXME: REEVALUTE THIS. - !isSafeToLoadUnconditionally(LoadPtr, UnavailablePred->getTerminator())) + !isSafeToLoadUnconditionally(LoadPtr, UnavailablePred->getTerminator())) { + assert(NewInsts.empty() && "Should not have inserted instructions"); return false; + } // Okay, we can eliminate this load by inserting a reload in the predecessor // and using PHI construction to get the value in the other predecessors, do // it. DEBUG(errs() << "GVN REMOVING PRE LOAD: " << *LI << '\n'); - + DEBUG(if (!NewInsts.empty()) + errs() << "INSERTED " << NewInsts.size() << " INSTS: " + << *NewInsts.back() << '\n'); + Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false, LI->getAlignment(), UnavailablePred->getTerminator()); |