Fix template bug in base::saturated_cast<>()

Perform template check with UnderlyingType and clamp shift value for SaturateFastAsmOp<>; TBR=servolk@chromium.org Change-Id: I8828b06a211515ee06d65c7dd1989b7cd84a841c Reviewed-on: https://chromium-review.googlesource.com/572870 Commit-Queue: Justin Schuh <jschuh@chromium.org> Reviewed-by: Justin Schuh <jschuh@chromium.org> Cr-Commit-Position: refs/heads/master@{#486998}
marcosholgado · Jul 15, 2017 · c77d482 · c77d482
1 parent 0bcc3cf
commit c77d482
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Showing 2 changed files with 8 additions and 9 deletions.
diff --git a/base/numerics/safe_conversions.h b/base/numerics/safe_conversions.h
@@ -13,9 +13,7 @@
 
 #include "base/numerics/safe_conversions_impl.h"
 
-// TODO(jschuh): Investigate why these were failing to build for ios.
-#if !defined(__APPLE__) && !defined(__native_client__) && \
-    (defined(__ARMEL__) || defined(__arch64__))
+#if !defined(__native_client__) && (defined(__ARMEL__) || defined(__arch64__))
 #include "base/numerics/safe_conversions_arm_impl.h"
 #define BASE_HAS_OPTIMIZED_SAFE_CONVERSIONS (1)
 #else
@@ -117,7 +115,7 @@ template <typename Dst,
 constexpr Dst saturated_cast(Src value) {
   using SrcType = typename UnderlyingType<Src>::type;
   return !IsCompileTimeConstant(value) &&
-                 SaturateFastAsmOp<Dst, Src>::is_supported &&
+                 SaturateFastAsmOp<Dst, SrcType>::is_supported &&
                  std::is_same<SaturationHandler<Dst>,
                               SaturationDefaultLimits<Dst>>::value
              ? SaturateFastAsmOp<Dst, SrcType>::Do(value)

diff --git a/base/numerics/safe_conversions_arm_impl.h b/base/numerics/safe_conversions_arm_impl.h
@@ -60,14 +60,15 @@ struct SaturateFastAsmOp {
     if (std::is_signed<Dst>::value) {
       asm("ssat %[dst], %[shift], %[src]"
           : [dst] "=r"(result)
-          : [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value));
+          : [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value <= 32
+                                            ? IntegerBitsPlusSign<Dst>::value
+                                            : 32));
     } else {
       asm("usat %[dst], %[shift], %[src]"
           : [dst] "=r"(result)
-          :
-          [src] "r"(src), [shift] "n"(std::is_same<uint32_t, Dst>::value
-                                          ? IntegerBitsPlusSign<Dst>::value - 1
-                                          : IntegerBitsPlusSign<Dst>::value));
+          : [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value < 32
+                                            ? IntegerBitsPlusSign<Dst>::value
+                                            : 31));
     }
     return static_cast<Dst>(result);
   }