Bug 1549667 - [mips] Fix unaligned load with sign/zero extend. r=lth

Reviewers: jandem, lth

Reviewed By: lth

Subscribers: jandem

Bug #: 1549667

Differential Revision: https://phabricator.services.mozilla.com/D30337

--HG--
extra : rebase_source : 1180d03984603a0498ad2f9f3dda8d907be85f6f
extra : histedit_source : 3dfd9666c1d43f521a1a147a6cfa60c23ec3b54e

js/src/jit/mips-shared/MacroAssembler-mips-shared.cpp

@@ -496,7 +496,7 @@ void MacroAssemblerMIPSShared::ma_load_unaligned(
   BufferOffset load;
   switch (size) {
     case SizeHalfWord:
-      if (extension != ZeroExtend) {
+      if (extension == ZeroExtend) {
         load = as_lbu(temp, base, hiOffset);
       } else {
         load = as_lb(temp, base, hiOffset);
@@ -508,7 +508,7 @@ void MacroAssemblerMIPSShared::ma_load_unaligned(
       load = as_lwl(dest, base, hiOffset);
       as_lwr(dest, base, lowOffset);
 #ifdef JS_CODEGEN_MIPS64
-      if (extension != ZeroExtend) {
+      if (extension == ZeroExtend) {
         as_dext(dest, dest, 0, 32);
       }
 #endif