From f38e48be60df22320035db330c7275d6dff4d6c2 Mon Sep 17 00:00:00 2001
From: yangguo <yangguo@chromium.org>
Date: Tue, 20 Jan 2015 05:53:34 -0800
Subject: [PATCH] Use fast_sqrt instead of std::sqrt in simulators.

This prevents clang from inlining and returning inconsistent results.

R=bmeurer@chromium.org
BUG=v8:3802
LOG=N

Review URL: https://codereview.chromium.org/831393006

Cr-Commit-Position: refs/heads/master@{#26158}
---
 src/arm/simulator-arm.cc       | 2 +-
 src/arm64/simulator-arm64.cc   | 3 ++-
 src/mips/simulator-mips.cc     | 3 ++-
 src/mips64/simulator-mips64.cc | 3 ++-
 src/ppc/simulator-ppc.cc       | 2 +-
 5 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/arm/simulator-arm.cc b/src/arm/simulator-arm.cc
index e34c311..50c42c3 100644
--- a/src/arm/simulator-arm.cc
+++ b/src/arm/simulator-arm.cc
@@ -3069,7 +3069,7 @@ void Simulator::DecodeTypeVFP(Instruction* instr) {
       } else if (((instr->Opc2Value() == 0x1)) && (instr->Opc3Value() == 0x3)) {
         // vsqrt
         double dm_value = get_double_from_d_register(vm);
-        double dd_value = std::sqrt(dm_value);
+        double dd_value = fast_sqrt(dm_value);
         dd_value = canonicalizeNaN(dd_value);
         set_d_register_from_double(vd, dd_value);
       } else if (instr->Opc3Value() == 0x0) {
diff --git a/src/arm64/simulator-arm64.cc b/src/arm64/simulator-arm64.cc
index bc524af..819a897 100644
--- a/src/arm64/simulator-arm64.cc
+++ b/src/arm64/simulator-arm64.cc
@@ -12,6 +12,7 @@
 #include "src/arm64/decoder-arm64-inl.h"
 #include "src/arm64/simulator-arm64.h"
 #include "src/assembler.h"
+#include "src/codegen.h"
 #include "src/disasm.h"
 #include "src/macro-assembler.h"
 #include "src/ostreams.h"
@@ -3100,7 +3101,7 @@ T Simulator::FPSqrt(T op) {
   } else if (op < 0.0) {
     return FPDefaultNaN<T>();
   } else {
-    return std::sqrt(op);
+    return fast_sqrt(op);
   }
 }
 
diff --git a/src/mips/simulator-mips.cc b/src/mips/simulator-mips.cc
index fabca67..79f337d 100644
--- a/src/mips/simulator-mips.cc
+++ b/src/mips/simulator-mips.cc
@@ -13,6 +13,7 @@
 
 #include "src/assembler.h"
 #include "src/base/bits.h"
+#include "src/codegen.h"
 #include "src/disasm.h"
 #include "src/mips/constants-mips.h"
 #include "src/mips/simulator-mips.h"
@@ -2244,7 +2245,7 @@ void Simulator::DecodeTypeRegister(Instruction* instr) {
               set_fpu_register_double(fd_reg, -fs);
               break;
             case SQRT_D:
-              set_fpu_register_double(fd_reg, sqrt(fs));
+              set_fpu_register_double(fd_reg, fast_sqrt(fs));
               break;
             case C_UN_D:
               set_fcsr_bit(fcsr_cc, std::isnan(fs) || std::isnan(ft));
diff --git a/src/mips64/simulator-mips64.cc b/src/mips64/simulator-mips64.cc
index 9899d47..8839917 100644
--- a/src/mips64/simulator-mips64.cc
+++ b/src/mips64/simulator-mips64.cc
@@ -13,6 +13,7 @@
 
 #include "src/assembler.h"
 #include "src/base/bits.h"
+#include "src/codegen.h"
 #include "src/disasm.h"
 #include "src/mips64/constants-mips64.h"
 #include "src/mips64/simulator-mips64.h"
@@ -2391,7 +2392,7 @@ void Simulator::DecodeTypeRegister(Instruction* instr) {
               set_fpu_register_double(fd_reg, -fs);
               break;
             case SQRT_D:
-              set_fpu_register_double(fd_reg, sqrt(fs));
+              set_fpu_register_double(fd_reg, fast_sqrt(fs));
               break;
             case C_UN_D:
               set_fcsr_bit(fcsr_cc, std::isnan(fs) || std::isnan(ft));
diff --git a/src/ppc/simulator-ppc.cc b/src/ppc/simulator-ppc.cc
index 0d10153..34c35d6 100644
--- a/src/ppc/simulator-ppc.cc
+++ b/src/ppc/simulator-ppc.cc
@@ -2613,7 +2613,7 @@ void Simulator::ExecuteExt4(Instruction* instr) {
       int frt = instr->RTValue();
       int frb = instr->RBValue();
       double frb_val = get_double_from_d_register(frb);
-      double frt_val = std::sqrt(frb_val);
+      double frt_val = fast_sqrt(frb_val);
       set_d_register_from_double(frt, frt_val);
       return;
     }
-- 
2.7.4