r105228 reduced the memcpy / memset inline limit to 4 with -Os to avoid blowing

up freebsd bootloader. However, this doesn't make much sense for Darwin, whose
-Os is meant to optimize for size only if it doesn't hurt performance.
rdar://8821501

llvm-svn: 122936

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 110812c4371..be2de0c00d6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -50,6 +50,7 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
 #include <algorithm>
 #include <cmath>
 using namespace llvm;
@@ -3286,8 +3287,14 @@ static bool FindOptimalMemOpLowering(std::vector<EVT> &MemOps,
   // the size of a call to memcpy or memset (3 arguments + call).
   if (Limit != ~0U) {
     const Function *F = DAG.getMachineFunction().getFunction();
-    if (F->hasFnAttr(Attribute::OptimizeForSize))
-      Limit = 4;
+    if (F->hasFnAttr(Attribute::OptimizeForSize)) {
+      Triple T(((LLVMTargetMachine&)TLI.getTargetMachine()).getTargetTriple());
+      if (T.getOS() != Triple::Darwin)
+        // A pretty terrible hack to defat the wild guess. On Darwin, -Os means
+        // optimize for size without hurting performance so we don't want to
+        // bump down the limit.
+        Limit = 4;
+    }
   }
 
   unsigned NumMemOps = 0;