[llvm-commits] [llvm] r94783 - in /llvm/trunk: lib/Transforms/Scalar/SimplifyLibCalls.cpp test/Transforms/SimplifyLibCalls/strcpy_chk.ll

[Eric Christopher]

Author: echristo
Date: Thu Jan 28 19:37:11 2010
New Revision: 94783

URL: http://llvm.org/viewvc/llvm-project?rev=94783&view=rev
Log:
Make strcpy_chk lower to strcpy if we have a safe size.

Added:
    llvm/trunk/test/Transforms/SimplifyLibCalls/strcpy_chk.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp?rev=94783&r1=94782&r2=94783&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp Thu Jan 28 19:37:11 2010
@@ -1203,9 +1203,6 @@
 
 struct StrCpyChkOpt : public LibCallOptimization {
   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    // These optimizations require TargetData.
-    if (!TD) return 0;
-
     const FunctionType *FT = Callee->getFunctionType();
     if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
         !isa<PointerType>(FT->getParamType(0)) ||
@@ -1217,8 +1214,13 @@
     if (!SizeCI)
       return 0;
     
-    // We don't have any length information, just lower to a plain strcpy.
-    if (SizeCI->isAllOnesValue())
+    // If a) we don't have any length information, or b) we know this will
+    // fit then just lower to a plain strcpy. Otherwise we'll keep our
+    // strcpy_chk call which may fail at runtime if the size is too long.
+    // TODO: It might be nice to get a maximum length out of the possible
+    // string lengths for varying.
+    if (SizeCI->isAllOnesValue() ||
+        SizeCI->getZExtValue() >= GetStringLength(CI->getOperand(2)))
       return EmitStrCpy(CI->getOperand(1), CI->getOperand(2), B);
 
     return 0;

Added: llvm/trunk/test/Transforms/SimplifyLibCalls/strcpy_chk.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyLibCalls/strcpy_chk.ll?rev=94783&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/SimplifyLibCalls/strcpy_chk.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyLibCalls/strcpy_chk.ll Thu Jan 28 19:37:11 2010
@@ -0,0 +1,12 @@
+; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
+ at a = common global [60 x i8] zeroinitializer, align 1 ; <[60 x i8]*> [#uses=1]
+ at .str = private constant [8 x i8] c"abcdefg\00"   ; <[8 x i8]*> [#uses=1]
+
+define i8* @foo() nounwind {
+; CHECK: @foo
+; CHECK-NEXT: call i8* @strcpy
+  %call = call i8* @__strcpy_chk(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i8* getelementptr inbounds ([8 x i8]* @.str, i32 0, i32 0), i32 60) ; <i8*> [#uses=1]
+  ret i8* %call
+}
+
+declare i8* @__strcpy_chk(i8*, i8*, i32) nounwind