PPC: [wasm] Fixes for embedded constant pools.

src/compiler/ppc/code-generator-ppc.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 1527 matching lines @@
       __ Push(r0, fp, kConstantPoolRegister);
       // Adjust FP to point to saved FP.
       __ subi(fp, sp, Operand(StandardFrameConstants::kConstantPoolOffset));
     } else {
       __ Push(r0, fp);
       __ mr(fp, sp);
     }
   } else if (descriptor->IsJSFunctionCall()) {
     __ Prologue(this->info()->GeneratePreagedPrologue(), ip);
   } else if (frame()->needs_frame()) {
-    __ StubPrologue(ip);
+    // TODO(mbrandy): Detect the case where we're not generating an
+    // exported wasm function -- so that we can leverage ip to set up
+    // the constant pool pointer register.

[titzer, 2016/01/13 09:17:40]

To detect the compilation of a WASM function, you can get output_code_kind()
from the CompilationInfo, but I'm not sure that's the right check. I get crashes
on PPC for the WASM mjsunit tests (where the wrappers are compiled) in the
register allocator with and without this change. I dug a bit but I don't really
understand how IP is used in generated code.

+    __ StubPrologue();
   } else {
     frame()->SetElidedFrameSizeInSlots(0);
   }
   frame_access_state()->SetFrameAccessToDefault();
 
   int stack_shrink_slots = frame()->GetSpillSlotCount();
   if (info()->is_osr()) {
     // TurboFan OSR-compiled functions cannot be entered directly.
     __ Abort(kShouldNotDirectlyEnterOsrFunction);
 
@@ skipping 281 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8