instcombine: Migrate strspn optimizations

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167568 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 88 insertions, 50 deletions

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index bacada58c1..7d652dea48 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -119,38 +119,6 @@ static bool IsOnlyUsedInEqualityComparison(Value *V, Value *With) {
 
 namespace {
 //===---------------------------------------===//
-// 'strspn' Optimizations
-
-struct StrSpnOpt : public LibCallOptimization {
-  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    FunctionType *FT = Callee->getFunctionType();
-    if (FT->getNumParams() != 2 ||
-        FT->getParamType(0) != B.getInt8PtrTy() ||
-        FT->getParamType(1) != FT->getParamType(0) ||
-        !FT->getReturnType()->isIntegerTy())
-      return 0;
-
-    StringRef S1, S2;
-    bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
-    bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
-
-    // strspn(s, "") -> 0
-    // strspn("", s) -> 0
-    if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
-      return Constant::getNullValue(CI->getType());
-
-    // Constant folding.
-    if (HasS1 && HasS2) {
-      size_t Pos = S1.find_first_not_of(S2);
-      if (Pos == StringRef::npos) Pos = S1.size();
-      return ConstantInt::get(CI->getType(), Pos);
-    }
-
-    return 0;
-  }
-};
-
-//===---------------------------------------===//
 // 'strcspn' Optimizations
 
 struct StrCSpnOpt : public LibCallOptimization {
@@ -1037,7 +1005,7 @@ namespace {
 
     StringMap<LibCallOptimization*> Optimizations;
     // String and Memory LibCall Optimizations
-    StrSpnOpt StrSpn; StrCSpnOpt StrCSpn; StrStrOpt StrStr;
+    StrCSpnOpt StrCSpn; StrStrOpt StrStr;
     MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
     // Math Library Optimizations
     CosOpt Cos; PowOpt Pow; Exp2Opt Exp2;
@@ -1105,7 +1073,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
 /// we know.
 void SimplifyLibCalls::InitOptimizations() {
   // String and Memory LibCall Optimizations
-  Optimizations["strspn"] = &StrSpn;
   Optimizations["strcspn"] = &StrCSpn;
   Optimizations["strstr"] = &StrStr;
   Optimizations["memcmp"] = &MemCmp;
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 581b8d3ea2..64c7011660 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -772,6 +772,35 @@ struct StrToOpt : public LibCallOptimization {
   }
 };
 
+struct StrSpnOpt : public LibCallOptimization {
+  virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    FunctionType *FT = Callee->getFunctionType();
+    if (FT->getNumParams() != 2 ||
+        FT->getParamType(0) != B.getInt8PtrTy() ||
+        FT->getParamType(1) != FT->getParamType(0) ||
+        !FT->getReturnType()->isIntegerTy())
+      return 0;
+
+    StringRef S1, S2;
+    bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
+    bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
+
+    // strspn(s, "") -> 0
+    // strspn("", s) -> 0
+    if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
+      return Constant::getNullValue(CI->getType());
+
+    // Constant folding.
+    if (HasS1 && HasS2) {
+      size_t Pos = S1.find_first_not_of(S2);
+      if (Pos == StringRef::npos) Pos = S1.size();
+      return ConstantInt::get(CI->getType(), Pos);
+    }
+
+    return 0;
+  }
+};
+
 } // End anonymous namespace.
 
 namespace llvm {
@@ -802,6 +831,7 @@ class LibCallSimplifierImpl {
   StrLenOpt StrLen;
   StrPBrkOpt StrPBrk;
   StrToOpt StrTo;
+  StrSpnOpt StrSpn;
 
   void initOptimizations();
 public:
@@ -842,6 +872,7 @@ void LibCallSimplifierImpl::initOptimizations() {
   Optimizations["strtoll"] = &StrTo;
   Optimizations["strtold"] = &StrTo;
   Optimizations["strtoull"] = &StrTo;
+  Optimizations["strspn"] = &StrSpn;
 }
 
 Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {
diff --git a/test/Transforms/InstCombine/strspn-1.ll b/test/Transforms/InstCombine/strspn-1.ll
new file mode 100644
index 0000000000..393f88735b
--- /dev/null
+++ b/test/Transforms/InstCombine/strspn-1.ll
@@ -0,0 +1,56 @@
+; Test that the strspn 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"
+
+@abcba = constant [6 x i8] c"abcba\00"
+@abc = constant [4 x i8] c"abc\00"
+@null = constant [1 x i8] zeroinitializer
+
+declare i64 @strspn(i8*, i8*)
+
+; Check strspn(s, "") -> 0.
+
+define i64 @test_simplify1(i8* %str) {
+; CHECK: @test_simplify1
+  %pat = getelementptr [1 x i8]* @null, i32 0, i32 0
+
+  %ret = call i64 @strspn(i8* %str, i8* %pat)
+  ret i64 %ret
+; CHECK-NEXT: ret i64 0
+}
+
+; Check strspn("", s) -> 0.
+
+define i64 @test_simplify2(i8* %pat) {
+; CHECK: @test_simplify2
+  %str = getelementptr [1 x i8]* @null, i32 0, i32 0
+
+  %ret = call i64 @strspn(i8* %str, i8* %pat)
+  ret i64 %ret
+; CHECK-NEXT: ret i64 0
+}
+
+; Check strspn(s1, s2), where s1 and s2 are constants.
+
+define i64 @test_simplify3() {
+; CHECK: @test_simplify3
+  %str = getelementptr [6 x i8]* @abcba, i32 0, i32 0
+  %pat = getelementptr [4 x i8]* @abc, i32 0, i32 0
+
+  %ret = call i64 @strspn(i8* %str, i8* %pat)
+  ret i64 %ret
+; CHECK-NEXT: ret i64 5
+}
+
+; Check cases that shouldn't be simplified.
+
+define i64 @test_no_simplify1(i8* %str, i8* %pat) {
+; CHECK: @test_no_simplify1
+
+  %ret = call i64 @strspn(i8* %str, i8* %pat)
+; CHECK-NEXT: %ret = call i64 @strspn(i8* %str, i8* %pat)
+  ret i64 %ret
+; CHECK-NEXT: ret i64 %ret
+}
diff --git a/test/Transforms/SimplifyLibCalls/StrSpn.ll b/test/Transforms/SimplifyLibCalls/StrSpn.ll
index 800c190883..2660ee9800 100644
--- a/test/Transforms/SimplifyLibCalls/StrSpn.ll
+++ b/test/Transforms/SimplifyLibCalls/StrSpn.ll
@@ -6,22 +6,6 @@ target datalayout = "-p:64:64:64"
 @abc = constant [4 x i8] c"abc\00"
 @null = constant [1 x i8] zeroinitializer
 
-declare i64 @strspn(i8*, i8*)
-
-define i64 @testspn(i8* %s1, i8* %s2) {
-  	%abcba_p = getelementptr [6 x i8]* @abcba, i32 0, i32 0
-	%abc_p = getelementptr [4 x i8]* @abc, i32 0, i32 0
-	%null_p = getelementptr [1 x i8]* @null, i32 0, i32 0
-	%test1 = call i64 @strspn(i8* %s1, i8* %null_p)
-	%test2 = call i64 @strspn(i8* %null_p, i8* %s2)
-	%test3 = call i64 @strspn(i8* %abcba_p, i8* %abc_p)
-; CHECK-NOT: call i64 @strspn
-	%test4 = call i64 @strspn(i8* %s1, i8* %s2)
-; CHECK: call i64 @strspn(i8* %s1, i8* %s2)
-	ret i64 %test3
-; CHECK: ret i64 5
-}
-
 declare i64 @strcspn(i8*, i8*)
 
 define i64 @testcspn(i8* %s1, i8* %s2) {