instcombine: Migrate strstr optimizations

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167682 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 83 insertions, 60 deletions

diff --git a/test/Transforms/InstCombine/strstr-1.ll b/test/Transforms/InstCombine/strstr-1.ll
new file mode 100644
index 0000000000..81f5271874
--- /dev/null
+++ b/test/Transforms/InstCombine/strstr-1.ll
@@ -0,0 +1,65 @@
+; Test that the strstr library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+@.str = private constant [1 x i8] zeroinitializer
+@.str1 = private constant [2 x i8] c"a\00"
+@.str2 = private constant [6 x i8] c"abcde\00"
+@.str3 = private constant [4 x i8] c"bcd\00"
+
+declare i8* @strstr(i8*, i8*)
+
+; Check strstr(str, "") -> str.
+
+define i8* @test_simplify1(i8* %str) {
+; CHECK: @test_simplify1
+  %pat = getelementptr inbounds [1 x i8]* @.str, i32 0, i32 0
+  %ret = call i8* @strstr(i8* %str, i8* %pat)
+  ret i8* %ret
+; CHECK-NEXT: ret i8* %str
+}
+
+; Check strstr(str, "a") -> strchr(str, 'a').
+
+define i8* @test_simplify2(i8* %str) {
+; CHECK: @test_simplify2
+  %pat = getelementptr inbounds [2 x i8]* @.str1, i32 0, i32 0
+  %ret = call i8* @strstr(i8* %str, i8* %pat)
+  ret i8* %ret
+; CHECK-NEXT: @strchr(i8* %str, i32 97)
+}
+
+; Check strstr("abcde", "bcd") -> "abcde" + 1.
+
+define i8* @test_simplify3() {
+; CHECK: @test_simplify3
+  %str = getelementptr inbounds [6 x i8]* @.str2, i32 0, i32 0
+  %pat = getelementptr inbounds [4 x i8]* @.str3, i32 0, i32 0
+  %ret = call i8* @strstr(i8* %str, i8* %pat)
+  ret i8* %ret
+; CHECK-NEXT: getelementptr inbounds ([6 x i8]* @.str2, i64 0, i64 1)
+}
+
+; Check strstr(str, str) -> str.
+
+define i8* @test_simplify4(i8* %str) {
+; CHECK: @test_simplify4
+  %ret = call i8* @strstr(i8* %str, i8* %str)
+  ret i8* %ret
+; CHECK-NEXT: ret i8* %str
+}
+
+; Check strstr(str, pat) == str -> strncmp(str, pat, strlen(str)) == 0.
+
+define i1 @test_simplify5(i8* %str, i8* %pat) {
+; CHECK: @test_simplify5
+  %ret = call i8* @strstr(i8* %str, i8* %pat)
+  %cmp = icmp eq i8* %ret, %str
+  ret i1 %cmp
+; CHECK: [[LEN:%[a-z]+]] = call {{i[0-9]+}} @strlen(i8* %pat)
+; CHECK: [[NCMP:%[a-z]+]] = call {{i[0-9]+}} @strncmp(i8* %str, i8* %pat, {{i[0-9]+}} [[LEN]])
+; CHECK: icmp eq {{i[0-9]+}} [[NCMP]], 0
+; CHECK: ret i1
+}
diff --git a/test/Transforms/InstCombine/strstr-2.ll b/test/Transforms/InstCombine/strstr-2.ll
new file mode 100644
index 0000000000..5092f9b4f8
--- /dev/null
+++ b/test/Transforms/InstCombine/strstr-2.ll
@@ -0,0 +1,18 @@
+; Test that the strstr library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+@null = private constant [1 x i8] zeroinitializer
+
+declare i8 @strstr(i8*, i8*)
+
+define i8 @test_no_simplify1(i8* %str) {
+; CHECK: @test_no_simplify1
+  %pat = getelementptr inbounds [1 x i8]* @null, i32 0, i32 0
+  %ret = call i8 @strstr(i8* %str, i8* %pat)
+; CHECK-NEXT: call i8 @strstr
+  ret i8 %ret
+; CHECK-NEXT: ret i8 %ret
+}
diff --git a/test/Transforms/SimplifyLibCalls/StrStr.ll b/test/Transforms/SimplifyLibCalls/StrStr.ll
deleted file mode 100644
index eefd2e8006..0000000000
--- a/test/Transforms/SimplifyLibCalls/StrStr.ll
+++ /dev/null
@@ -1,60 +0,0 @@
-; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
-; PR5783
-
-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"
-target triple = "i386-apple-darwin9.0"
-
-@.str = private constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
-@.str1 = private constant [2 x i8] c"a\00"        ; <[2 x i8]*> [#uses=1]
-@.str2 = private constant [6 x i8] c"abcde\00"    ; <[6 x i8]*> [#uses=1]
-@.str3 = private constant [4 x i8] c"bcd\00"      ; <[4 x i8]*> [#uses=1]
-
-define i8* @test1(i8* %P) nounwind readonly {
-entry:
-  %call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([1 x i8]* @.str, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
-  ret i8* %call
-; strstr(P, "") -> P
-; CHECK: @test1
-; CHECK: ret i8* %P
-}
-
-declare i8* @strstr(i8*, i8* nocapture) nounwind readonly
-
-define i8* @test2(i8* %P) nounwind readonly {
-entry:
-  %call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([2 x i8]* @.str1, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
-  ret i8* %call
-; strstr(P, "a") -> strchr(P, 'a')
-; CHECK: @test2
-; CHECK: @strchr(i8* %P, i32 97)
-}
-
-define i8* @test3(i8* nocapture %P) nounwind readonly {
-entry:
-  %call = tail call i8* @strstr(i8* getelementptr inbounds ([6 x i8]* @.str2, i32 0, i32 0), i8* getelementptr inbounds ([4 x i8]* @.str3, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
-  ret i8* %call
-; strstr("abcde", "bcd") -> "abcde"+1
-; CHECK: @test3
-; CHECK: getelementptr inbounds ([6 x i8]* @.str2, i32 0, i64 1)
-}
-
-define i8* @test4(i8* %P) nounwind readonly {
-entry:
-  %call = tail call i8* @strstr(i8* %P, i8* %P) nounwind ; <i8*> [#uses=1]
-  ret i8* %call
-; strstr(P, P) -> P
-; CHECK: @test4
-; CHECK: ret i8* %P
-}
-
-define i1 @test5(i8* %P, i8* %Q) nounwind readonly {
-entry:
-  %call = tail call i8* @strstr(i8* %P, i8* %Q) nounwind ; <i8*> [#uses=1]
-  %cmp = icmp eq i8* %call, %P
-  ret i1 %cmp
-; CHECK: @test5
-; CHECK: [[LEN:%[a-z]+]] = call {{i[0-9]+}} @strlen(i8* %Q)
-; CHECK: [[NCMP:%[a-z]+]] = call {{i[0-9]+}} @strncmp(i8* %P, i8* %Q, {{i[0-9]+}} [[LEN]])
-; CHECK: icmp eq {{i[0-9]+}} [[NCMP]], 0
-; CHECK: ret i1
-}