instcombine: Migrate memcmp optimizations

This patch migrates the memcmp optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167683 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 86 insertions, 39 deletions

diff --git a/test/Transforms/InstCombine/memcmp-1.ll b/test/Transforms/InstCombine/memcmp-1.ll
new file mode 100644
index 0000000000..862fd3a85a
--- /dev/null
+++ b/test/Transforms/InstCombine/memcmp-1.ll
@@ -0,0 +1,63 @@
+; Test that the memcmp library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+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"
+
+@foo = constant [4 x i8] c"foo\00"
+@hel = constant [4 x i8] c"hel\00"
+@hello_u = constant [8 x i8] c"hello_u\00"
+
+declare i32 @memcmp(i8*, i8*, i32)
+
+; Check memcmp(mem, mem, size) -> 0.
+
+define i32 @test_simplify1(i8* %mem, i32 %size) {
+; CHECK: @test_simplify1
+  %ret = call i32 @memcmp(i8* %mem, i8* %mem, i32 %size)
+  ret i32 %ret
+; CHECK: ret i32 0
+}
+
+; Check memcmp(mem1, mem2, 0) -> 0.
+
+define i32 @test_simplify2(i8* %mem1, i8* %mem2) {
+; CHECK: @test_simplify2
+  %ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 0)
+  ret i32 %ret
+; CHECK: ret i32 0
+}
+
+;; Check memcmp(mem1, mem2, 1) -> *(unsigned char*)mem1 - *(unsigned char*)mem2.
+
+define i32 @test_simplify3(i8* %mem1, i8* %mem2) {
+; CHECK: @test_simplify3
+  %ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 1)
+; CHECK: [[LOAD1:%[a-z]+]] = load i8* %mem1, align 1
+; CHECK: [[ZEXT1:%[a-z]+]] = zext i8 [[LOAD1]] to i32
+; CHECK: [[LOAD2:%[a-z]+]] = load i8* %mem2, align 1
+; CHECK: [[ZEXT2:%[a-z]+]] = zext i8 [[LOAD2]] to i32
+; CHECK: [[RET:%[a-z]+]] = sub i32 [[ZEXT1]], [[ZEXT2]]
+  ret i32 %ret
+; CHECK: ret i32 [[RET]]
+}
+
+; Check memcmp(mem1, mem2, size) -> cnst, where all arguments are constants.
+
+define i32 @test_simplify4() {
+; CHECK: @test_simplify4
+  %mem1 = getelementptr [4 x i8]* @hel, i32 0, i32 0
+  %mem2 = getelementptr [8 x i8]* @hello_u, i32 0, i32 0
+  %ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 3)
+  ret i32 %ret
+; CHECK: ret i32 0
+}
+
+define i32 @test_simplify5() {
+; CHECK: @test_simplify5
+  %mem1 = getelementptr [4 x i8]* @hel, i32 0, i32 0
+  %mem2 = getelementptr [4 x i8]* @foo, i32 0, i32 0
+  %ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 3)
+  ret i32 %ret
+; CHECK: ret i32 2
+}
diff --git a/test/Transforms/InstCombine/memcmp-2.ll b/test/Transforms/InstCombine/memcmp-2.ll
new file mode 100644
index 0000000000..3796117bc2
--- /dev/null
+++ b/test/Transforms/InstCombine/memcmp-2.ll
@@ -0,0 +1,17 @@
+; Test that the memcmp library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+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"
+
+declare i32* @memcmp(i8*, i8*, i32)
+
+; Check that memcmp functions with the wrong prototype aren't simplified.
+
+define i32* @test_no_simplify1(i8* %mem, i32 %size) {
+; CHECK: @test_no_simplify1
+  %ret = call i32* @memcmp(i8* %mem, i8* %mem, i32 %size)
+; CHECK-NEXT: call i32* @memcmp
+  ret i32* %ret
+; CHECK-NEXT: ret i32* %ret
+}
diff --git a/test/Transforms/InstCombine/strncmp-1.ll b/test/Transforms/InstCombine/strncmp-1.ll
index 48b26d1a5f..187c2fa50e 100644
--- a/test/Transforms/InstCombine/strncmp-1.ll
+++ b/test/Transforms/InstCombine/strncmp-1.ll
@@ -67,12 +67,14 @@ define i32 @test5() {
 }
 
 ; strncmp(x,y,1) -> memcmp(x,y,1)
-; TODO: Once the memcmp simplifier gets moved into the instcombine pass
-; the following memcmp will be folded into two loads and a subtract.
 define i32 @test6(i8* %str1, i8* %str2) {
 ; CHECK: @test6
-; CHECK: call i32 @memcmp
-; CHECK: ret i32 %memcmp
+; CHECK: [[LOAD1:%[a-z]+]] = load i8* %str1, align 1
+; CHECK: [[ZEXT1:%[a-z]+]] = zext i8 [[LOAD1]] to i32
+; CHECK: [[LOAD2:%[a-z]+]] = load i8* %str2, align 1
+; CHECK: [[ZEXT2:%[a-z]+]] = zext i8 [[LOAD2]] to i32
+; CHECK: [[RET:%[a-z]+]] = sub i32 [[ZEXT1]], [[ZEXT2]]
+; CHECK: ret i32 [[RET]]
 
   %temp1 = call i32 @strncmp(i8* %str1, i8* %str2, i32 1)
   ret i32 %temp1
diff --git a/test/Transforms/SimplifyLibCalls/memcmp.ll b/test/Transforms/SimplifyLibCalls/memcmp.ll
deleted file mode 100644
index 6ca4dc97a1..0000000000
--- a/test/Transforms/SimplifyLibCalls/memcmp.ll
+++ /dev/null
@@ -1,35 +0,0 @@
-; Test that the memcmpOptimizer works correctly
-; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
-
-@h = constant [2 x i8] c"h\00"		; <[2 x i8]*> [#uses=0]
-@hel = constant [4 x i8] c"hel\00"		; <[4 x i8]*> [#uses=0]
-@hello_u = constant [8 x i8] c"hello_u\00"		; <[8 x i8]*> [#uses=0]
-
-declare i32 @memcmp(i8*, i8*, i32)
-
-define void @test(i8* %P, i8* %Q, i32 %N, i32* %IP, i1* %BP) {
-	%A = call i32 @memcmp( i8* %P, i8* %P, i32 %N )		; <i32> [#uses=1]
-; CHECK-NOT: call {{.*}} memcmp
-; CHECK: store volatile
-	store volatile i32 %A, i32* %IP
-	%B = call i32 @memcmp( i8* %P, i8* %Q, i32 0 )		; <i32> [#uses=1]
-; CHECK-NOT: call {{.*}} memcmp
-; CHECK: store volatile
-	store volatile i32 %B, i32* %IP
-	%C = call i32 @memcmp( i8* %P, i8* %Q, i32 1 )		; <i32> [#uses=1]
-; CHECK: load
-; CHECK: zext
-; CHECK: load
-; CHECK: zext
-; CHECK: sub
-; CHECK: store volatile
-	store volatile i32 %C, i32* %IP
-  %F = call i32 @memcmp(i8* getelementptr ([4 x i8]* @hel, i32 0, i32 0),
-                        i8* getelementptr ([8 x i8]* @hello_u, i32 0, i32 0),
-                        i32 3)
-; CHECK-NOT: call {{.*}} memcmp
-; CHECK: store volatile
-  store volatile i32 %F, i32* %IP
-	ret void
-}
-