PPC: fix DCHECK failure on reg aliasing

Junliang Yan · Commit Bot · commit 4b0f5711ec08 · 2018-08-28T17:54:44.000Z
Change-Id: I2df302a4bed3775dfdf15cc3d1797c50229cc997 Reviewed-on: https://chromium-review.googlesource.com/1194582 Reviewed-by: Joran Siu <joransiu@ca.ibm.com> Commit-Queue: Junliang Yan <jyan@ca.ibm.com> Cr-Commit-Position: refs/heads/master@{#55469}
diff --git a/src/ppc/macro-assembler-ppc.cc b/src/ppc/macro-assembler-ppc.cc
@@ -2908,10 +2908,14 @@ void TurboAssembler::SwapP(Register src, MemOperand dst, Register scratch) {
 
 void TurboAssembler::SwapP(MemOperand src, MemOperand dst, Register scratch_0,
                            Register scratch_1) {
-  if (src.ra() != r0) DCHECK(!AreAliased(src.ra(), scratch_0, scratch_1));
-  if (src.rb() != r0) DCHECK(!AreAliased(src.rb(), scratch_0, scratch_1));
-  if (dst.ra() != r0) DCHECK(!AreAliased(dst.ra(), scratch_0, scratch_1));
-  if (dst.rb() != r0) DCHECK(!AreAliased(dst.rb(), scratch_0, scratch_1));
+  if (src.ra() != r0 && src.ra().is_valid())
+    DCHECK(!AreAliased(src.ra(), scratch_0, scratch_1));
+  if (src.rb() != r0 && src.rb().is_valid())
+    DCHECK(!AreAliased(src.rb(), scratch_0, scratch_1));
+  if (dst.ra() != r0 && dst.ra().is_valid())
+    DCHECK(!AreAliased(dst.ra(), scratch_0, scratch_1));
+  if (dst.rb() != r0 && dst.rb().is_valid())
+    DCHECK(!AreAliased(dst.rb(), scratch_0, scratch_1));
   DCHECK(!AreAliased(scratch_0, scratch_1));
   if (is_int16(src.offset()) || is_int16(dst.offset())) {
     if (!is_int16(src.offset())) {
