Fixed bug when custom lowering DEC64m on x86.

If the DEC node had more than one user, it was doing this lowering but
leaving the original DEC node around and so decrementing twice.

Fixes PR11964.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150356 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 830cb65878e2d00b5ed9f6ce48d42016e9550747..709be5f8530d75d7ebf7324002f00e39654b8ae7 100644 (file)
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -2378,6 +2378,7 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
         Chain->getOpcode() != ISD::LOAD ||
         StoredVal->getOpcode() != X86ISD::DEC ||
         StoredVal.getResNo() != 0 ||
+        !StoredVal.getNode()->hasNUsesOfValue(1, 0) ||
         StoredVal->getOperand(0).getNode() != Chain.getNode())
       break;
 

diff --git a/test/CodeGen/X86/dec-eflags-lower.ll b/test/CodeGen/X86/dec-eflags-lower.ll
index 458160a4bfc005e63d33b91879736d56cf509da1..841a4615f53992b7e2ef3b4bda0ed17d89e97792 100644 (file)
--- a/test/CodeGen/X86/dec-eflags-lower.ll
+++ b/test/CodeGen/X86/dec-eflags-lower.ll
@@ -2,6 +2,7 @@
 
 %struct.obj = type { i64 }
 
+; CHECK: _Z7releaseP3obj
 define void @_Z7releaseP3obj(%struct.obj* nocapture %o) nounwind uwtable ssp {
 entry:
 ; CHECK: decq  (%{{rdi|rcx}})
@@ -22,8 +23,31 @@ return:                                           ; preds = %entry, %if.end
   ret void
 }
 
+@c = common global i64 0, align 8
+@a = common global i32 0, align 4
+@.str = private unnamed_addr constant [5 x i8] c"%ld\0A\00", align 1
+@b = common global i32 0, align 4
+
+; CHECK: test
+define i32 @test() nounwind uwtable ssp {
+entry:
+; CHECK: decq
+; CHECK-NOT: decq
+%0 = load i64* @c, align 8, !tbaa !0
+%dec.i = add nsw i64 %0, -1
+store i64 %dec.i, i64* @c, align 8, !tbaa !0
+%tobool.i = icmp ne i64 %dec.i, 0
+%lor.ext.i = zext i1 %tobool.i to i32
+store i32 %lor.ext.i, i32* @a, align 4, !tbaa !3
+%call = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([5 x i8]* @.str, i64 0, i64 0), i64 %dec.i) nounwind
+ret i32 0
+}
+
+declare i32 @printf(i8* nocapture, ...) nounwind
+
 declare void @free(i8* nocapture) nounwind
 
 !0 = metadata !{metadata !"long", metadata !1}
 !1 = metadata !{metadata !"omnipotent char", metadata !2}
 !2 = metadata !{metadata !"Simple C/C++ TBAA", null}
+!3 = metadata !{metadata !"int", metadata !1}