PR9055: extend the fix to PR4050 (r70179) to apply to zext and anyext.

Returning a new node makes the code try to replace the old node, which
in the included testcase is killed by CSE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129650 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 378c13b030171e308abe13f74d4c283bede76ddb..f42751167a450784ab1272a8786941dea7f3706e 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3884,7 +3884,7 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
         // CombineTo deleted the truncate, if needed, but not what's under it.
         AddToWorkList(oye);
       }
-      return DAG.getNode(ISD::ZERO_EXTEND, N->getDebugLoc(), VT, NarrowLoad);
+      return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }
 
@@ -4112,7 +4112,7 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
         // CombineTo deleted the truncate, if needed, but not what's under it.
         AddToWorkList(oye);
       }
-      return DAG.getNode(ISD::ANY_EXTEND, N->getDebugLoc(), VT, NarrowLoad);
+      return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }
 

diff --git a/test/CodeGen/X86/fold-zext-trunc.ll b/test/CodeGen/X86/fold-zext-trunc.ll
new file mode 100644 (file)
index 0000000..f901ad2
--- /dev/null
+++ b/test/CodeGen/X86/fold-zext-trunc.ll
@@ -0,0 +1,23 @@
+; RUN: llc < %s | FileCheck %s
+; PR9055
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
+target triple = "i686-pc-linux-gnu"
+
+%struct.S0 = type { i32, [2 x i8], [2 x i8], [4 x i8] }
+
+@g_98 = common global %struct.S0 zeroinitializer, align 4
+
+define void @foo() nounwind {
+; CHECK: movzbl
+; CHECK-NOT: movzbl
+; CHECK: calll
+entry:
+  %tmp17 = load i8* getelementptr inbounds (%struct.S0* @g_98, i32 0, i32 1, i32 0), align 4
+  %tmp54 = zext i8 %tmp17 to i32
+  %foo = load i32* bitcast (i8* getelementptr inbounds (%struct.S0* @g_98, i32 0, i32 1, i32 0) to i32*), align 4
+  %conv.i = trunc i32 %foo to i8
+  tail call void @func_12(i32 %tmp54, i8 zeroext %conv.i) nounwind
+  ret void
+}
+
+declare void @func_12(i32, i8 zeroext)