Treat objc selector reference globals as invariant so that MachineLICM can hoist...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143600 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index a240667..a2fd3c4 100644 (file)
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1232,6 +1232,19 @@ bool MachineInstr::hasVolatileMemoryRef() const {
   return false;
 }
 
+/// pointsToRuntimeConstantMemory - Return true if this value points to data
+/// which does never changes once the program starts running
+static bool pointsToRuntimeConstantMemory(const Value *V) {
+  if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+    StringRef Name = GV->getName();
+    // These special values are known to be constant at runtime
+    // TODO: a new linkage type for these would be far better than this check
+    if (Name.startswith("\01L_OBJC_SELECTOR_REFERENCES_"))
+      return true;
+  }
+  return false;
+}
+
 /// isInvariantLoad - Return true if this instruction is loading from a
 /// location whose value is invariant across the function.  For example,
 /// loading a value from the constant pool or from the argument area
@@ -1259,6 +1272,8 @@ bool MachineInstr::isInvariantLoad(AliasAnalysis *AA) const {
       if (const PseudoSourceValue *PSV = dyn_cast<PseudoSourceValue>(V))
         if (PSV->isConstant(MFI))
           continue;
+      if (pointsToRuntimeConstantMemory(V))
+        continue;
       // If we have an AliasAnalysis, ask it whether the memory is constant.
       if (AA && AA->pointsToConstantMemory(
                       AliasAnalysis::Location(V, (*I)->getSize(),

diff --git a/test/CodeGen/X86/MachineLICM-HoistSelectorRefs.ll b/test/CodeGen/X86/MachineLICM-HoistSelectorRefs.ll
new file mode 100644 (file)
index 0000000..bb0e0f2
--- /dev/null
+++ b/test/CodeGen/X86/MachineLICM-HoistSelectorRefs.ll
@@ -0,0 +1,30 @@
+; RUN: llc < %s -march=x86-64 -mattr=+sse3,+sse41 -stats |& grep {1 machine-licm}
+; rdar://6027699
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.7.2"
+
+; STATS: 1 machine-licm
+
+@"\01L_OBJC_METH_VAR_NAME_" = internal global [4 x i8] c"foo\00", section "__TEXT,__objc_methname,cstring_literals", align 1
+@"\01L_OBJC_SELECTOR_REFERENCES_" = internal global i8* getelementptr inbounds ([4 x i8]* @"\01L_OBJC_METH_VAR_NAME_", i64 0, i64 0), section "__DATA, __objc_selrefs, literal_pointers, no_dead_strip"
+@"\01L_OBJC_IMAGE_INFO" = internal constant [2 x i32] [i32 0, i32 16], section "__DATA, __objc_imageinfo, regular, no_dead_strip"
+@llvm.used = appending global [3 x i8*] [i8* getelementptr inbounds ([4 x i8]* @"\01L_OBJC_METH_VAR_NAME_", i32 0, i32 0), i8* bitcast (i8** @"\01L_OBJC_SELECTOR_REFERENCES_" to i8*), i8* bitcast ([2 x i32]* @"\01L_OBJC_IMAGE_INFO" to i8*)], section "llvm.metadata"
+
+define void @test(i8* %x) uwtable ssp {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %0 = load i8** @"\01L_OBJC_SELECTOR_REFERENCES_", align 8
+  %call = tail call i8* bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to i8* (i8*, i8*)*)(i8* %x, i8* %0)
+  %inc = add i32 %i.01, 1
+  %exitcond = icmp eq i32 %inc, 10000
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+
+declare i8* @objc_msgSend(i8*, i8*, ...) nonlazybind