[llvm-commits] [llvm] r45912 - in /llvm/trunk: lib/Transforms/Utils/InlineFunction.cpp test/Transforms/Inline/byval2.ll

[Chris Lattner]

Author: lattner
Date: Sat Jan 12 12:54:29 2008
New Revision: 45912

URL: http://llvm.org/viewvc/llvm-project?rev=45912&view=rev
Log:
we don't have to make an explicit copy of a byval argument when 
inlining a function if we know that the function does not write
to *any* memory.  This implements test/Transforms/Inline/byval2.ll

Added:
    llvm/trunk/test/Transforms/Inline/byval2.ll
Modified:
    llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp

Modified: llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp?rev=45912&r1=45911&r2=45912&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp Sat Jan 12 12:54:29 2008
@@ -241,10 +241,12 @@
       Value *ActualArg = *AI;
       
       // When byval arguments actually inlined, we need to make the copy implied
-      // by them actually explicit.
-      // TODO: If we know that the callee never modifies the struct, we can
-      // remove this copy.
-      if (CalledFunc->paramHasAttr(ArgNo+1, ParamAttr::ByVal)) {
+      // by them explicit.  However, we don't do this if the callee is readonly
+      // or readnone, because the copy would be unneeded: the callee doesn't
+      // modify the struct.
+      if (CalledFunc->paramHasAttr(ArgNo+1, ParamAttr::ByVal) &&
+          !CalledFunc->paramHasAttr(0, ParamAttr::ReadOnly) &&
+          !CalledFunc->paramHasAttr(0, ParamAttr::ReadNone)) {
         const Type *AggTy = cast<PointerType>(I->getType())->getElementType();
         const Type *VoidPtrTy = PointerType::getUnqual(Type::Int8Ty);
         

Added: llvm/trunk/test/Transforms/Inline/byval2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/byval2.ll?rev=45912&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/Inline/byval2.ll (added)
+++ llvm/trunk/test/Transforms/Inline/byval2.ll Sat Jan 12 12:54:29 2008
@@ -0,0 +1,28 @@
+; RUN: llvm-as < %s | opt -inline | llvm-dis | not grep {llvm.memcpy}
+
+; Inlining a byval struct should NOT cause an explicit copy 
+; into an alloca if the function is readonly
+
+	%struct.ss = type { i32, i64 }
+ at .str = internal constant [10 x i8] c"%d, %lld\0A\00"		; <[10 x i8]*> [#uses=1]
+
+define internal i32 @f(%struct.ss* byval  %b) nounwind readonly {
+entry:
+	%tmp = getelementptr %struct.ss* %b, i32 0, i32 0		; <i32*> [#uses=2]
+	%tmp1 = load i32* %tmp, align 4		; <i32> [#uses=1]
+	%tmp2 = add i32 %tmp1, 1		; <i32> [#uses=1]
+	ret i32 %tmp2
+}
+
+declare i32 @printf(i8*, ...) nounwind 
+
+define i32 @main() nounwind  {
+entry:
+	%S = alloca %struct.ss		; <%struct.ss*> [#uses=4]
+	%tmp1 = getelementptr %struct.ss* %S, i32 0, i32 0		; <i32*> [#uses=1]
+	store i32 1, i32* %tmp1, align 8
+	%tmp4 = getelementptr %struct.ss* %S, i32 0, i32 1		; <i64*> [#uses=1]
+	store i64 2, i64* %tmp4, align 4
+	%X = call i32 @f( %struct.ss* byval  %S ) nounwind 
+	ret i32 %X
+}