[llvm] r334268 - [DAGCombine] Fix for PR37667

[Sam Parker via llvm-commits]

Author: sam_parker
Date: Fri Jun  8 00:49:04 2018
New Revision: 334268

URL: http://llvm.org/viewvc/llvm-project?rev=334268&view=rev
Log:
[DAGCombine] Fix for PR37667

While trying to propagate AND masks back to loads, we currently allow
one non-load node to be included as a leaf in chain. This fix now
limits that node to produce only a single data value.

Differential Revision: https://reviews.llvm.org/D47878

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/X86/backpropmask.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=334268&r1=334267&r2=334268&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Fri Jun  8 00:49:04 2018
@@ -3997,7 +3997,23 @@ bool DAGCombiner::SearchForAndLoads(SDNo
     // Allow one node which will masked along with any loads found.
     if (NodeToMask)
       return false;
+ 
+    // Also ensure that the node to be masked only produces one data result. 
     NodeToMask = Op.getNode();
+    if (NodeToMask->getNumValues() > 1) {
+      bool HasValue = false;
+      for (unsigned i = 0, e = NodeToMask->getNumValues(); i < e; ++i) {
+        MVT VT = SDValue(NodeToMask, i).getSimpleValueType();
+        if (VT != MVT::Glue && VT != MVT::Other) {
+          if (HasValue) {
+            NodeToMask = nullptr;
+            return false;
+          }
+          HasValue = true;
+        }
+      }
+      assert(HasValue && "Node to be masked has no data result?");
+    }
   }
   return true;
 }

Modified: llvm/trunk/test/CodeGen/X86/backpropmask.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/backpropmask.ll?rev=334268&r1=334267&r2=334268&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/backpropmask.ll (original)
+++ llvm/trunk/test/CodeGen/X86/backpropmask.ll Fri Jun  8 00:49:04 2018
@@ -1,11 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
 
-; FIXME:
-; Verify that backwards propagation of a mask does not affect
-; nodes with multiple result values. In both tests, the stored
-; 32-bit value should be masked to an 8-bit number (and 255).
-
 @b = local_unnamed_addr global i32 918, align 4
 @d = local_unnamed_addr global i32 8089, align 4
 @c = common local_unnamed_addr global i32 0, align 4
@@ -14,12 +9,12 @@
 define void @PR37667() {
 ; CHECK-LABEL: PR37667:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movzbl {{.*}}(%rip), %ecx
 ; CHECK-NEXT:    movl {{.*}}(%rip), %eax
 ; CHECK-NEXT:    xorl %edx, %edx
 ; CHECK-NEXT:    divl {{.*}}(%rip)
-; CHECK-NEXT:    orl %ecx, %edx
-; CHECK-NEXT:    movl %edx, {{.*}}(%rip)
+; CHECK-NEXT:    orl {{.*}}(%rip), %edx
+; CHECK-NEXT:    movzbl %dl, %eax
+; CHECK-NEXT:    movl %eax, {{.*}}(%rip)
 ; CHECK-NEXT:    retq
   %t0 = load i32, i32* @c, align 4
   %t1 = load i32, i32* @b, align 4
@@ -37,8 +32,8 @@ define void @PR37060() {
 ; CHECK-NEXT:    movl $-1, %eax
 ; CHECK-NEXT:    cltd
 ; CHECK-NEXT:    idivl {{.*}}(%rip)
-; CHECK-NEXT:    movzbl {{.*}}(%rip), %eax
-; CHECK-NEXT:    xorl %edx, %eax
+; CHECK-NEXT:    xorl {{.*}}(%rip), %edx
+; CHECK-NEXT:    movzbl %dl, %eax
 ; CHECK-NEXT:    movl %eax, {{.*}}(%rip)
 ; CHECK-NEXT:    retq
   %t0 = load i32, i32* @c, align 4