Index: llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp =================================================================== --- llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp +++ llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp @@ -1797,6 +1797,41 @@ return true; } + // Check for same values, when both BaseValue and CurrentValue are phi nodes. + // PHI nodes that have the same incoming values, and belonging to the same + // basic blocks are essentially the same SSA value. Such an example of same + // BaseValue, CurrentValue phis is created by findBasePointer, when a phi has + // incoming values with different base pointers. This phi is marked as + // conflict, and hence an additional phi with the same incoming values get + // generated. We need to identify the BaseValue (.base version of phi) and + // CurrentValue (the phi node itself) as the same, so that we can + // rematerialize the gep and casts below. + if (PHINode *CurrentPhi = dyn_cast(CurrentValue)) + if (PHINode *BasePhi = dyn_cast(BaseValue)) { + auto PhiNum = CurrentPhi->getNumIncomingValues(); + if (PhiNum != BasePhi->getNumIncomingValues() || + CurrentPhi->getParent() != BasePhi->getParent()) + return false; + // Map of incoming values and their corresponding basic blocks of + // CurrentPhi. + SmallDenseMap CurrentIncomingValues; + for (unsigned i = 0; i < PhiNum; i++) + CurrentIncomingValues[CurrentPhi->getIncomingValue(i)] = + CurrentPhi->getIncomingBlock(i); + + // Both current and base PHIs should have same incoming values and + // the same basic blocks corresponding to the incoming values. + for (unsigned i = 0; i < PhiNum; i++) { + auto CIVI = CurrentIncomingValues.find(BasePhi->getIncomingValue(i)); + if (CIVI == CurrentIncomingValues.end()) + return false; + BasicBlock *CurrentIncomingBB = CIVI->second; + if (CurrentIncomingBB != BasePhi->getIncomingBlock(i)) + return false; + } + return true; + } + if (GetElementPtrInst *GEP = dyn_cast(CurrentValue)) { ChainToBase.push_back(GEP); return findRematerializableChainToBasePointer(ChainToBase, Index: llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll =================================================================== --- llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll +++ llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll @@ -259,3 +259,40 @@ call void @use_obj32(i32 addrspace(1)* %ptr.gep11) ret void } + + +declare i32 addrspace(1)* @new_instance() nounwind "gc-leaf-function" + +; remat the gep in presence of base pointer which is a phi node. +; FIXME: We should remove the extra basephi.base as well. +define void @contains_basephi(i1 %cond) gc "statepoint-example" { +; CHECK-LABEL: contains_basephi +entry: + %base1 = call i32 addrspace(1)* @new_instance() + %base2 = call i32 addrspace(1)* @new_instance() + br i1 %cond, label %here, label %there + +here: + br label %merge + +there: + br label %merge + +merge: + ; CHECK: %basephi.base = phi i32 addrspace(1)* [ %base1, %here ], [ %base2, %there ], !is_base_value !0 + ; CHECK: %basephi = phi i32 addrspace(1)* [ %base1, %here ], [ %base2, %there ] + ; CHECK: %ptr.gep = getelementptr i32, i32 addrspace(1)* %basephi, i32 15 + ; CHECK: %statepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint + ; CHECK: %basephi.base.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %statepoint_token, i32 7, i32 7) ; (%basephi.base, %basephi.base) + ; CHECK: %basephi.base.relocated.casted = bitcast i8 addrspace(1)* %basephi.base.relocated to i32 addrspace(1)* + ; CHECK: %ptr.gep.remat = getelementptr i32, i32 addrspace(1)* %basephi, i32 15 + ; CHECK: call void @use_obj32(i32 addrspace(1)* %ptr.gep.remat) + + + + %basephi = phi i32 addrspace(1)* [ %base1, %here ], [ %base2, %there ] + %ptr.gep = getelementptr i32, i32 addrspace(1)* %basephi, i32 15 + call void @do_safepoint() ["deopt"() ] + call void @use_obj32(i32 addrspace(1)* %ptr.gep) + ret void +}