Contribution of PowerPC port.

src/base/cpu.cc

Index: src/base/cpu.cc
diff --git a/src/base/cpu.cc b/src/base/cpu.cc
index 20aeeee42bf76308b928418bac3a33fba3a93d4a..3690d9a103ea094529a866bc8e1d4d940dca9125 100644
--- a/src/base/cpu.cc
+++ b/src/base/cpu.cc
@@ -13,6 +13,9 @@
 #if V8_OS_QNX
 #include <sys/syspage.h>  // cpuinfo
 #endif
+#if V8_OS_LINUX && V8_HOST_ARCH_PPC
+#include <elf.h>
+#endif
 
 #include <ctype.h>
 #include <limits.h>
@@ -248,6 +251,7 @@ CPU::CPU() : stepping_(0),
              implementer_(0),
              architecture_(0),
              part_(0),
+             cache_line_size_(0),

[danno, 2014/07/29 13:24:08]

Seems like it makes sense to add a sentinel constant here, e.g.
UNKOWN_CACHE_LINE_SIZE = 0.

[andrew_low, 2014/07/30 13:27:05]

Seems sensible, I've made what I believe are the changes you're asking for. 

On 2014/07/29 13:24:08, danno wrote:

              has_fpu_(false),
              has_cmov_(false),
              has_sahf_(false),
@@ -493,6 +497,64 @@ CPU::CPU() : stepping_(0),
     delete[] part;
   }
 
+#elif V8_HOST_ARCH_PPC
+
+#if V8_OS_LINUX && !defined(USE_SIMULATOR)
+  // Read processor info from /proc/self/auxv.
+  char *auxv_cpu_type = NULL;
+  unsigned auxv_cache_line_size = 0;
+  FILE* fp = fopen("/proc/self/auxv", "r");
+  if (fp != NULL) {
+#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;
+      } else if (entry.a_type == AT_DCACHEBSIZE ||
+                 entry.a_type == AT_ICACHEBSIZE ||
+                 entry.a_type == AT_UCACHEBSIZE) {
+        unsigned cachebsize = entry.a_un.a_val;
+        if (cachebsize > 0 &&
+            (auxv_cache_line_size == 0 || cachebsize < auxv_cache_line_size)) {
+          auxv_cache_line_size = cachebsize;
+        }
+      }
+    }
+    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) {
+      part_ = PPC_POWER7;
+    } else if (strcmp(auxv_cpu_type, "power6") == 0) {
+      part_ = PPC_POWER6;
+    } else if (strcmp(auxv_cpu_type, "power5") == 0) {
+      part_ = PPC_POWER5;
+    } else if (strcmp(auxv_cpu_type, "ppc970") == 0) {
+      part_ = PPC_G5;
+    } else if (strcmp(auxv_cpu_type, "ppc7450") == 0) {
+      part_ = PPC_G4;
+    } else if (strcmp(auxv_cpu_type, "pa6t") == 0) {
+      part_ = PPC_PA6T;
+    }
+  }
+
+  if (auxv_cache_line_size > 0) {
+    cache_line_size_ = auxv_cache_line_size;
+  }
+#endif
+
 #endif
 }