Reland PPC portion of "Detect cache line size on Linux for PPC hosts."

src/base/cpu.cc

 // Copyright 2013 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/base/cpu.h"
 
 #if V8_LIBC_MSVCRT
 #include <intrin.h>  // __cpuid()
 #endif
 #if V8_OS_LINUX
@@ skipping 294 matching lines @@
     : stepping_(0),
       model_(0),
       ext_model_(0),
       family_(0),
       ext_family_(0),
       type_(0),
       implementer_(0),
       architecture_(0),
       variant_(-1),
       part_(0),
+      icache_line_size_(UNKNOWN_CACHE_LINE_SIZE),
+      dcache_line_size_(UNKNOWN_CACHE_LINE_SIZE),
       has_fpu_(false),
       has_cmov_(false),
       has_sahf_(false),
       has_mmx_(false),
       has_sse_(false),
       has_sse2_(false),
       has_sse3_(false),
       has_ssse3_(false),
       has_sse41_(false),
       has_sse42_(false),
@@ skipping 312 matching lines @@
 #if V8_TARGET_ARCH_PPC64
     Elf64_auxv_t entry;
 #else
     Elf32_auxv_t entry;
 #endif
     for (;;) {
       size_t n = fread(&entry, sizeof(entry), 1, fp);
       if (n == 0 || entry.a_type == AT_NULL) {
         break;
       }
-      if (entry.a_type == AT_PLATFORM) {
-        auxv_cpu_type = reinterpret_cast<char*>(entry.a_un.a_val);
-        break;
+      switch (entry.a_type) {
+        case AT_PLATFORM:
+          auxv_cpu_type = reinterpret_cast<char*>(entry.a_un.a_val);
+          break;
+        case AT_ICACHEBSIZE:
+          icache_line_size_ = entry.a_un.a_val;
+          break;
+        case AT_DCACHEBSIZE:
+          dcache_line_size_ = entry.a_un.a_val;
+          break;
       }
     }
     fclose(fp);
   }
 
   part_ = -1;
   if (auxv_cpu_type) {
     if (strcmp(auxv_cpu_type, "power8") == 0) {
       part_ = PPC_POWER8;
     } else if (strcmp(auxv_cpu_type, "power7") == 0) {
@@ skipping 26 matching lines @@
       part_ = PPC_POWER5;
       break;
   }
 #endif  // V8_OS_AIX
 #endif  // !USE_SIMULATOR
 #endif  // V8_HOST_ARCH_PPC
 }
 
 }  // namespace base
 }  // namespace v8