diff options
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 30 | ||||
| -rw-r--r-- | test/Transforms/GVN/pre-load.ll | 28 |
2 files changed, 33 insertions, 25 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()); diff --git a/test/Transforms/GVN/pre-load.ll b/test/Transforms/GVN/pre-load.ll index c055e86b42..aa9e2b0cb0 100644 --- a/test/Transforms/GVN/pre-load.ll +++ b/test/Transforms/GVN/pre-load.ll @@ -86,9 +86,9 @@ block1: block2: br label %block4 -; HECK: block2: -; HECK: load i32* -; HECK: br label %block4 +; CHECK: block2: +; CHECK: load i32* +; CHECK: br label %block4 block3: %B = getelementptr i32* %q, i32 1 @@ -103,10 +103,10 @@ block4: %P3 = getelementptr i32* %P2, i32 1 %PRE = load i32* %P3 ret i32 %PRE -; HECK: block4: -; HECK-NEXT: phi i32 [ -; HECK-NOT: load -; HECK: ret i32 +; CHECK: block4: +; CHECK-NEXT: phi i32 [ +; CHECK-NOT: load +; CHECK: ret i32 } ;void test5(int N, double *G) { @@ -248,9 +248,9 @@ block1: block2: br label %block4 -; HECK: block2: -; HECK: load i32* -; HECK: br label %block4 +; CHECK: block2: +; CHECK: load i32* +; CHECK: br label %block4 block3: %A = getelementptr i32* %p, i32 1 @@ -262,10 +262,10 @@ block4: %P3 = getelementptr i32* %P2, i32 1 %PRE = load i32* %P3 ret i32 %PRE -; HECK: block4: -; HECK-NEXT: phi i32 [ -; HECK-NOT: load -; HECK: ret i32 +; CHECK: block4: +; CHECK-NEXT: phi i32 [ +; CHECK-NOT: load +; CHECK: ret i32 } |