[PATCH] D58705: [X86] Don't peek through bitcasts before checking ISD::isBuildVectorOfConstantSDNodes in combineTruncatedArithmetic

[Craig Topper via Phabricator via llvm-commits]

craig.topper updated this revision to Diff 188603.
craig.topper added a comment.

Add test case


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58705/new/

https://reviews.llvm.org/D58705

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/X86/pr40891.ll


Index: test/CodeGen/X86/pr40891.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/pr40891.ll
@@ -0,0 +1,22 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-unknown-unknown -mattr=avx2 | FileCheck %s
+
+; Make sure this sequence doesn't hang in DAG combine.
+
+define <8 x i32> @foo(<8 x i64> %x, <4 x i64> %y) {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vandps %ymm2, %ymm0, %ymm0
+; CHECK-NEXT:    vandps {{\.LCPI.*}}, %ymm1, %ymm1
+; CHECK-NEXT:    vextractf128 $1, %ymm0, %xmm2
+; CHECK-NEXT:    vshufps {{.*#+}} xmm0 = xmm0[0,2],xmm2[0,2]
+; CHECK-NEXT:    vextractf128 $1, %ymm1, %xmm2
+; CHECK-NEXT:    vshufps {{.*#+}} xmm1 = xmm1[0,2],xmm2[0,2]
+; CHECK-NEXT:    vinsertf128 $1, %xmm1, %ymm0, %ymm0
+; CHECK-NEXT:    retl
+  %a = shufflevector <4 x i64> %y, <4 x i64> <i64 12345, i64 67890, i64 13579, i64 24680>, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+  %b = and <8 x i64> %x, %a
+  %c = trunc <8 x i64> %b to <8 x i32>
+  ret <8 x i32> %c
+}
+
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -38717,8 +38717,7 @@
       return true;
 
     // See if this is a single use constant which can be constant folded.
-    SDValue BC = peekThroughOneUseBitcasts(Op);
-    return ISD::isBuildVectorOfConstantSDNodes(BC.getNode());
+    return ISD::isBuildVectorOfConstantSDNodes(Op.getNode());
   };
 
   auto TruncateArithmetic = [&](SDValue N0, SDValue N1) {


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