[X86] Conditionalize Darwin MaxVectorAlign on the presence of AVX.

There's no point in using a larger alignment if we have no instructions
that would benefit from it.

Differential Revision: http://reviews.llvm.org/D12389

llvm-svn: 246229

1 files changed, 19 insertions, 2 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index 985e991e601..503e529bfe2 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -3629,13 +3629,21 @@ public:
     LongDoubleWidth = 128;
     LongDoubleAlign = 128;
     SuitableAlign = 128;
-    MaxVectorAlign = 256;
     SizeType = UnsignedLong;
     IntPtrType = SignedLong;
     DataLayoutString = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128";
     HasAlignMac68kSupport = true;
   }
 
+  bool handleTargetFeatures(std::vector<std::string> &Features,
+                            DiagnosticsEngine &Diags) override {
+    if (!DarwinTargetInfo<X86_32TargetInfo>::handleTargetFeatures(Features,
+                                                                  Diags))
+      return false;
+    // Now that we know if we have AVX, we can decide how to align vectors.
+    MaxVectorAlign = hasFeature("avx") ? 256 : 128;
+    return true;
+  }
 };
 
 // x86-32 Windows target
@@ -3986,13 +3994,22 @@ public:
   DarwinX86_64TargetInfo(const llvm::Triple &Triple)
       : DarwinTargetInfo<X86_64TargetInfo>(Triple) {
     Int64Type = SignedLongLong;
-    MaxVectorAlign = 256;
     // The 64-bit iOS simulator uses the builtin bool type for Objective-C.
     llvm::Triple T = llvm::Triple(Triple);
     if (T.isiOS())
       UseSignedCharForObjCBool = false;
     DataLayoutString = "e-m:o-i64:64-f80:128-n8:16:32:64-S128";
   }
+
+  bool handleTargetFeatures(std::vector<std::string> &Features,
+                            DiagnosticsEngine &Diags) override {
+    if (!DarwinTargetInfo<X86_64TargetInfo>::handleTargetFeatures(Features,
+                                                                  Diags))
+      return false;
+    // Now that we know if we have AVX, we can decide how to align vectors.
+    MaxVectorAlign = hasFeature("avx") ? 256 : 128;
+    return true;
+  }
 };
 
 class OpenBSDX86_64TargetInfo : public OpenBSDTargetInfo<X86_64TargetInfo> {