rewrite the memset_pattern pattern generation stuff to accept any 2/4/8/16-byte

constant, including globals.  This makes us generate much more "pretty" pattern
globals as well because it doesn't break it down to an array of bytes all the
time.

This enables us to handle stores of relocatable globals.  This kicks in about
48 times in 254.gap, giving us stuff like this:

@.memset_pattern40 = internal constant [2 x %struct.TypHeader* (%struct.TypHeader*, %struct.TypHeader*)*] [%struct.TypHeader* (%struct.TypHeader*, %struct
.TypHeader*)* @IsFalse, %struct.TypHeader* (%struct.TypHeader*, %struct.TypHeader*)* @IsFalse], align 16

...
  call void @memset_pattern16(i8* %scevgep5859, i8* bitcast ([2 x %struct.TypHeader* (%struct.TypHeader*, %struct.TypHeader*)*]* @.memset_pattern40 to i8*
), i64 %tmp75) nounwind



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126044 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/LoopIdiomRecognize.cpp

@@ -388,43 +388,24 @@ static Constant *getMemSetPatternValue(Value *V, const TargetData &TD) {
   if (Size == 0 || (Size & 7) || (Size & (Size-1)))
     return 0;
   
-  // Convert the constant to an integer type of the appropriate size so we can
-  // start hacking on it.
-  if (isa<PointerType>(V->getType()))
-    C = ConstantExpr::getPtrToInt(C, IntegerType::get(C->getContext(), Size));
-  else if (isa<VectorType>(V->getType()) || V->getType()->isFloatingPointTy())
-    C = ConstantExpr::getBitCast(C, IntegerType::get(C->getContext(), Size));
-  else if (!isa<IntegerType>(V->getType()))
-    return 0;  // Unhandled type.
+  // Don't care enough about darwin/ppc to implement this.
+  if (TD.isBigEndian())
+    return 0;
 
   // Convert to size in bytes.
   Size /= 8;
-  
-  // If we couldn't fold this to an integer, we fail.  We don't bother to handle
-  // relocatable expressions like the address of a global yet.
-  // FIXME!
-  ConstantInt *CI = dyn_cast<ConstantInt>(C);
-  if (CI == 0) return 0;
 
-  APInt CVal = CI->getValue();
-  
   // TODO: If CI is larger than 16-bytes, we can try slicing it in half to see
-  // if the top and bottom are the same.
+  // if the top and bottom are the same (e.g. for vectors and large integers).
   if (Size > 16) return 0;
+  
+  // If the constant is exactly 16 bytes, just use it.
+  if (Size == 16) return C;
 
-  // If this is a big endian target (PPC) then we need to bswap.
-  if (TD.isBigEndian())
-    CVal = CVal.byteSwap();
-  
-  // Determine what each byte of the pattern value should be.
-  char Value[16];
-  for (unsigned i = 0; i != 16; ++i) {
-    // Get the byte value we're indexing into.
-    unsigned CByte = i % Size;
-    Value[i] = (unsigned char)(CVal.getZExtValue() >> CByte);
-  }
-  
-  return ConstantArray::get(V->getContext(), StringRef(Value, 16), false);
+  // Otherwise, we'll use an array of the constants.
+  unsigned ArraySize = 16/Size;
+  ArrayType *AT = ArrayType::get(V->getType(), ArraySize);
+  return ConstantArray::get(AT, std::vector<Constant*>(ArraySize, C));
 }
 
 
@@ -518,8 +499,7 @@ processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
                                             PatternValue, ".memset_pattern");
     GV->setUnnamedAddr(true); // Ok to merge these.
     GV->setAlignment(16);
-    Value *PatternPtr = Builder.CreateConstInBoundsGEP2_32(GV, 0, 0, "pattern");
-    
+    Value *PatternPtr = ConstantExpr::getBitCast(GV, Builder.getInt8PtrTy());
     NewCall = Builder.CreateCall3(MSP, BasePtr, PatternPtr, NumBytes);
   }
   

test/Transforms/LoopIdiom/basic.ll

@@ -277,7 +277,7 @@ for.end13:                                        ; preds = %for.inc10
 ; On darwin10 (which is the triple in this .ll file) this loop can be turned
 ; into a memset_pattern call.
 ; rdar://9009151
-define void @test11(i32* nocapture %P) nounwind ssp {
+define void @test11_pattern(i32* nocapture %P) nounwind ssp {
 entry:
   br label %for.body
 
@@ -291,7 +291,7 @@ for.body:                                         ; preds = %entry, %for.body
 
 for.end:                                          ; preds = %for.body
   ret void
-; CHECK: @test11
+; CHECK: @test11_pattern
 ; CHECK-NEXT: entry:
 ; CHECK-NEXT: bitcast
 ; CHECK-NEXT: memset_pattern
@@ -322,3 +322,28 @@ for.end:                                          ; preds = %for.body
 ; CHECK: ret void
 }
 
+@G = global i32 5
+
+; This store-of-address loop can be turned into a memset_pattern call.
+; rdar://9009151
+define void @test13_pattern(i32** nocapture %P) nounwind ssp {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %indvar = phi i64 [ 0, %entry ], [ %indvar.next, %for.body ]
+  %arrayidx = getelementptr i32** %P, i64 %indvar
+  store i32* @G, i32** %arrayidx, align 4
+  %indvar.next = add i64 %indvar, 1
+  %exitcond = icmp eq i64 %indvar.next, 10000
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+; CHECK: @test13_pattern
+; CHECK-NEXT: entry:
+; CHECK-NEXT: bitcast
+; CHECK-NEXT: memset_pattern
+; CHECK-NOT: store
+; CHECK: ret void
+}