[llvm] r235509 - [X86][AVX] Fix failure due to a missing ISel pattern to select VBROADCAST nodes (PR23259).

[Andrea Di Biagio]

Author: adibiagio
Date: Wed Apr 22 09:53:39 2015
New Revision: 235509

URL: http://llvm.org/viewvc/llvm-project?rev=235509&view=rev
Log:
[X86][AVX] Fix failure due to a missing ISel pattern to select VBROADCAST nodes (PR23259).

This fixes a regression introduced at revision 218263.

On AVX, if we optimize for size, a splat build_vector of a load
is lowered into a VBROADCAST node. This is done even if the value type of the
splat build_vector node is v2i64.

Since AVX doesn't support v2f64/v2i64 broadcasts, revision 218263 added two
extra tablegen patterns to allow selecting a VMOVDDUPrm from an X86VBroadcast
where the scalar element comes from a loadi64/loadf64.

However, revision 218263 forgot to add an extra fallback pattern for the case
where we have a X86VBroadcast of a loadi64 with multiple uses.

This patch adds the missing tablegen pattern in X86InstrSSE.td.
This patch also adds an extra test to 'splat-for-size.ll' to verify that ISel
doesn't crash with a 'fatal error in the backend' due to a missing AVX pattern
to select v2i64 X86ISD::BROADCAST nodes.

Modified:
    llvm/trunk/lib/Target/X86/X86InstrSSE.td
    llvm/trunk/test/CodeGen/X86/splat-for-size.ll

Modified: llvm/trunk/lib/Target/X86/X86InstrSSE.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrSSE.td?rev=235509&r1=235508&r2=235509&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrSSE.td (original)
+++ llvm/trunk/lib/Target/X86/X86InstrSSE.td Wed Apr 22 09:53:39 2015
@@ -5223,9 +5223,9 @@ let Predicates = [HasAVX] in {
 
 let Predicates = [UseAVX, OptForSize] in {
   def : Pat<(v2f64 (X86VBroadcast (loadf64 addr:$src))),
-  (VMOVDDUPrm addr:$src)>;
+            (VMOVDDUPrm addr:$src)>;
   def : Pat<(v2i64 (X86VBroadcast (loadi64 addr:$src))),
-  (VMOVDDUPrm addr:$src)>;
+            (VMOVDDUPrm addr:$src)>;
 }
 
 let Predicates = [UseSSE3] in {
@@ -8478,6 +8478,8 @@ let Predicates = [HasAVX] in {
 
   def : Pat<(v2f64 (X86VBroadcast f64:$src)),
             (VMOVDDUPrr (COPY_TO_REGCLASS FR64:$src, VR128))>;
+  def : Pat<(v2i64 (X86VBroadcast i64:$src)),
+            (VMOVDDUPrr (COPY_TO_REGCLASS GR64:$src, VR128))>;
 }
 
 //===----------------------------------------------------------------------===//

Modified: llvm/trunk/test/CodeGen/X86/splat-for-size.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/splat-for-size.ll?rev=235509&r1=235508&r2=235509&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/splat-for-size.ll (original)
+++ llvm/trunk/test/CodeGen/X86/splat-for-size.ll Wed Apr 22 09:53:39 2015
@@ -138,4 +138,18 @@ define <32 x i8> @splat_v32i8(<32 x i8>
 ; CHECK: retq
 }
 
+; PR23259: Verify that ISel doesn't crash with a 'fatal error in backend'
+; due to a missing AVX pattern to select a v2i64 X86ISD::BROADCAST of a
+; loadi16 with multiple uses.
+
+ at A = common global <3 x i64> zeroinitializer, align 32
+
+define <8 x i64> @pr23259() #0 {
+entry:
+  %0 = load <4 x i64>, <4 x i64>* bitcast (<3 x i64>* @A to <4 x i64>*), align 32
+  %1 = shufflevector <4 x i64> %0, <4 x i64> undef, <3 x i32> <i32 undef, i32 undef, i32 2>
+  %shuffle = shufflevector <3 x i64> <i64 1, i64 undef, i64 undef>, <3 x i64> %1, <8 x i32> <i32 5, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0>
+  ret <8 x i64> %shuffle
+}
+
 attributes #0 = { optsize }