teach objectsize about strdup() and strndup()

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160676 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 64 insertions, 3 deletions

diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp
index 8d99ec3e56..4833b5212b 100644
--- a/lib/Analysis/MemoryBuiltins.cpp
+++ b/lib/Analysis/MemoryBuiltins.cpp
@@ -64,7 +64,7 @@ static const AllocFnsTy AllocationFnData[] = {
   {"realloc",             ReallocLike, 2, 1,  -1},
   {"reallocf",            ReallocLike, 2, 1,  -1},
   {"strdup",              StrDupLike,  1, -1, -1},
-  {"strndup",             StrDupLike,  2, -1, -1}
+  {"strndup",             StrDupLike,  2, 1,  -1}
 };
 
 
@@ -414,8 +414,21 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
 
   // handle strdup-like functions separately
   if (FnData->AllocTy == StrDupLike) {
-    // TODO
-    return unknown();
+    APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
+    if (!Size)
+      return unknown();
+
+    // strndup limits strlen
+    if (FnData->FstParam > 0) {
+      ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
+      if (!Arg)
+        return unknown();
+
+      APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
+      if (Size.ugt(MaxSize))
+        Size = MaxSize + 1;
+    }
+    return std::make_pair(Size, Zero);
   }
 
   ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
diff --git a/test/Transforms/InstCombine/objsize.ll b/test/Transforms/InstCombine/objsize.ll
index f5a4581377..1818d8978d 100644
--- a/test/Transforms/InstCombine/objsize.ll
+++ b/test/Transforms/InstCombine/objsize.ll
@@ -171,3 +171,51 @@ define i32 @test8(i8** %esc) {
 ; CHECK: ret i32 30
   ret i32 %objsize
 }
+
+declare noalias i8* @strdup(i8* nocapture) nounwind
+declare noalias i8* @strndup(i8* nocapture, i32) nounwind
+
+; CHECK: @test9
+define i32 @test9(i8** %esc) {
+  %call = tail call i8* @strdup(i8* getelementptr inbounds ([8 x i8]* @.str, i64 0, i64 0)) nounwind
+  store i8* %call, i8** %esc, align 8
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %call, i1 true)
+; CHECK: ret i32 8
+  ret i32 %1
+}
+
+; CHECK: @test10
+define i32 @test10(i8** %esc) {
+  %call = tail call i8* @strndup(i8* getelementptr inbounds ([8 x i8]* @.str, i64 0, i64 0), i32 3) nounwind
+  store i8* %call, i8** %esc, align 8
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %call, i1 true)
+; CHECK: ret i32 4
+  ret i32 %1
+}
+
+; CHECK: @test11
+define i32 @test11(i8** %esc) {
+  %call = tail call i8* @strndup(i8* getelementptr inbounds ([8 x i8]* @.str, i64 0, i64 0), i32 7) nounwind
+  store i8* %call, i8** %esc, align 8
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %call, i1 true)
+; CHECK: ret i32 8
+  ret i32 %1
+}
+
+; CHECK: @test12
+define i32 @test12(i8** %esc) {
+  %call = tail call i8* @strndup(i8* getelementptr inbounds ([8 x i8]* @.str, i64 0, i64 0), i32 8) nounwind
+  store i8* %call, i8** %esc, align 8
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %call, i1 true)
+; CHECK: ret i32 8
+  ret i32 %1
+}
+
+; CHECK: @test13
+define i32 @test13(i8** %esc) {
+  %call = tail call i8* @strndup(i8* getelementptr inbounds ([8 x i8]* @.str, i64 0, i64 0), i32 57) nounwind
+  store i8* %call, i8** %esc, align 8
+  %1 = tail call i32 @llvm.objectsize.i32(i8* %call, i1 true)
+; CHECK: ret i32 8
+  ret i32 %1
+}