instcombine: Migrate stpcpy optimizations

This patch migrates the stpcpy optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.  Note that the
__stpcpy_chk simplifications were migrated in a previous commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167083 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 71 insertions, 3 deletions

diff --git a/test/Transforms/InstCombine/stpcpy-1.ll b/test/Transforms/InstCombine/stpcpy-1.ll
new file mode 100644
index 0000000..8b6bb0e
--- /dev/null
+++ b/test/Transforms/InstCombine/stpcpy-1.ll
@@ -0,0 +1,46 @@
+; Test that the stpcpy library call simplifier works correctly.
+; RUN: opt < %s -instcombine -S | FileCheck %s
+;
+; This transformation requires the pointer size, as it assumes that size_t is
+; the size of a pointer.
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
+
+@hello = constant [6 x i8] c"hello\00"
+@a = common global [32 x i8] zeroinitializer, align 1
+@b = common global [32 x i8] zeroinitializer, align 1
+
+declare i8* @stpcpy(i8*, i8*)
+
+define i8* @test_simplify1() {
+; CHECK: @test_simplify1
+
+  %dst = getelementptr [32 x i8]* @a, i32 0, i32 0
+  %src = getelementptr [6 x i8]* @hello, i32 0, i32 0
+
+  %ret = call i8* @stpcpy(i8* %dst, i8* %src)
+; CHECK: @llvm.memcpy.p0i8.p0i8.i32
+; CHECK-NEXT: getelementptr inbounds ([32 x i8]* @a, i32 0, i32 5)
+  ret i8* %ret
+}
+
+define i8* @test_simplify2() {
+; CHECK: @test_simplify2
+
+  %dst = getelementptr [32 x i8]* @a, i32 0, i32 0
+
+  %ret = call i8* @stpcpy(i8* %dst, i8* %dst)
+; CHECK: [[LEN:%[a-z]+]] = call i32 @strlen
+; CHECK-NEXT: getelementptr inbounds [32 x i8]* @a, i32 0, i32 [[LEN]]
+  ret i8* %ret
+}
+
+define i8* @test_no_simplify1() {
+; CHECK: @test_no_simplify1
+
+  %dst = getelementptr [32 x i8]* @a, i32 0, i32 0
+  %src = getelementptr [32 x i8]* @b, i32 0, i32 0
+
+  %ret = call i8* @stpcpy(i8* %dst, i8* %src)
+; CHECK: call i8* @stpcpy
+  ret i8* %ret
+}
diff --git a/test/Transforms/InstCombine/stpcpy-2.ll b/test/Transforms/InstCombine/stpcpy-2.ll
new file mode 100644
index 0000000..2e92c08
--- /dev/null
+++ b/test/Transforms/InstCombine/stpcpy-2.ll
@@ -0,0 +1,22 @@
+; Test that the stpcpy library call simplifier works correctly.
+; RUN: opt < %s -instcombine -S | FileCheck %s
+;
+; This transformation requires the pointer size, as it assumes that size_t is
+; the size of a pointer.
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
+
+@hello = constant [6 x i8] c"hello\00"
+@a = common global [32 x i8] zeroinitializer, align 1
+
+declare i16* @stpcpy(i8*, i8*)
+
+define void @test_no_simplify1() {
+; CHECK: @test_no_simplify1
+
+  %dst = getelementptr [32 x i8]* @a, i32 0, i32 0
+  %src = getelementptr [6 x i8]* @hello, i32 0, i32 0
+
+  call i16* @stpcpy(i8* %dst, i8* %src)
+; CHECK: call i16* @stpcpy
+  ret void
+}
diff --git a/test/Transforms/InstCombine/stpcpy_chk-1.ll b/test/Transforms/InstCombine/stpcpy_chk-1.ll
index d06b328..0560391 100644
--- a/test/Transforms/InstCombine/stpcpy_chk-1.ll
+++ b/test/Transforms/InstCombine/stpcpy_chk-1.ll
@@ -16,7 +16,7 @@ define void @test_simplify1() {
   %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [12 x i8]* @.str, i32 0, i32 0
 
-; CHECK-NEXT: call i8* @stpcpy
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32
   call i8* @__stpcpy_chk(i8* %dst, i8* %src, i32 60)
   ret void
 }
@@ -26,7 +26,7 @@ define void @test_simplify2() {
   %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [12 x i8]* @.str, i32 0, i32 0
 
-; CHECK-NEXT: call i8* @stpcpy
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32
   call i8* @__stpcpy_chk(i8* %dst, i8* %src, i32 12)
   ret void
 }
@@ -36,7 +36,7 @@ define void @test_simplify3() {
   %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [12 x i8]* @.str, i32 0, i32 0
 
-; CHECK-NEXT: call i8* @stpcpy
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i32
   call i8* @__stpcpy_chk(i8* %dst, i8* %src, i32 -1)
   ret void
 }