misched: better alias analysis.

This fixes a hole in the "cheap" alias analysis logic implemented within
the DAG builder itself, regardless of whether proper alias analysis is
enabled. It now handles this pattern produced by LSR+CodeGenPrepare.

%sunkaddr1 = ptrtoint * %obj to i64
%sunkaddr2 = add i64 %sunkaddr1, %lsr.iv
%sunkaddr3 = inttoptr i64 %sunkaddr2 to i32*
store i32 %v, i32* %sunkaddr3

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168768 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index 683011d3de..e46ca94647 100644
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -67,7 +67,7 @@ static const Value *getUnderlyingObjectFromInt(const Value *V) {
       // regular getUnderlyingObjectFromInt.
       if (U->getOpcode() == Instruction::PtrToInt)
         return U->getOperand(0);
-      // If we find an add of a constant or a multiplied value, it's
+      // If we find an add of a constant, a multiplied value, or a phi, it's
       // likely that the other operand will lead us to the base
       // object. We don't have to worry about the case where the
       // object address is somehow being computed by the multiply,
@@ -75,7 +75,8 @@ static const Value *getUnderlyingObjectFromInt(const Value *V) {
       // identifiable object.
       if (U->getOpcode() != Instruction::Add ||
           (!isa<ConstantInt>(U->getOperand(1)) &&
-           Operator::getOpcode(U->getOperand(1)) != Instruction::Mul))
+           Operator::getOpcode(U->getOperand(1)) != Instruction::Mul &&
+           !isa<PHINode>(U->getOperand(1))))
         return V;
       V = U->getOperand(0);
     } else {