From 6722f5e5b315dfd065573f5910315e631ce93baf Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Mon, 12 Jan 2015 17:20:06 +0000
Subject: [SimplifyLibCalls] Factor out str/mem libcall optimizations.

Put them in a separate function, so we can reuse them to further
simplify fortified libcalls as well.

Differential Revision: http://reviews.llvm.org/D6540

llvm-svn: 225639
---
 llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp | 106 +++++++++++++++----------
 1 file changed, 64 insertions(+), 42 deletions(-)

(limited to 'llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp')

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 930f6665770..fd654423f0e 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2060,53 +2060,18 @@ bool LibCallSimplifier::hasFloatVersion(StringRef FuncName) {
   return false;
 }
 
-Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
-  if (CI->isNoBuiltin())
-    return nullptr;
-
+Value *LibCallSimplifier::optimizeStringMemoryLibCall(CallInst *CI,
+                                                      IRBuilder<> &Builder) {
   LibFunc::Func Func;
   Function *Callee = CI->getCalledFunction();
   StringRef FuncName = Callee->getName();
-  IRBuilder<> Builder(CI);
-  bool isCallingConvC = CI->getCallingConv() == llvm::CallingConv::C;
-
-  // Command-line parameter overrides function attribute.
-  if (EnableUnsafeFPShrink.getNumOccurrences() > 0)
-    UnsafeFPShrink = EnableUnsafeFPShrink;
-  else if (Callee->hasFnAttribute("unsafe-fp-math")) {
-    // FIXME: This is the same problem as described in optimizeSqrt().
-    // If calls gain access to IR-level FMF, then use that instead of a
-    // function attribute.
-
-    // Check for unsafe-fp-math = true.
-    Attribute Attr = Callee->getFnAttribute("unsafe-fp-math");
-    if (Attr.getValueAsString() == "true")
-      UnsafeFPShrink = true;
-  }
-
-  // First, check for intrinsics.
-  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
-    if (!isCallingConvC)
-      return nullptr;
-    switch (II->getIntrinsicID()) {
-    case Intrinsic::pow:
-      return optimizePow(CI, Builder);
-    case Intrinsic::exp2:
-      return optimizeExp2(CI, Builder);
-    case Intrinsic::fabs:
-      return optimizeFabs(CI, Builder);
-    case Intrinsic::sqrt:
-      return optimizeSqrt(CI, Builder);
-    default:
-      return nullptr;
-    }
-  }
 
-  // Then check for known library functions.
+  // Check for string/memory library functions.
   if (TLI->getLibFunc(FuncName, Func) && TLI->has(Func)) {
-    // We never change the calling convention.
-    if (!ignoreCallingConv(Func) && !isCallingConvC)
-      return nullptr;
+    // Make sure we never change the calling convention.
+    assert((ignoreCallingConv(Func) ||
+            CI->getCallingConv() == llvm::CallingConv::C) &&
+      "Optimizing string/memory libcall would change the calling convention");
     switch (Func) {
     case LibFunc::strcat:
       return optimizeStrCat(CI, Builder);
@@ -2152,6 +2117,63 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
       return optimizeMemMove(CI, Builder);
     case LibFunc::memset:
       return optimizeMemSet(CI, Builder);
+    default:
+      break;
+    }
+  }
+  return nullptr;
+}
+
+Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
+  if (CI->isNoBuiltin())
+    return nullptr;
+
+  LibFunc::Func Func;
+  Function *Callee = CI->getCalledFunction();
+  StringRef FuncName = Callee->getName();
+  IRBuilder<> Builder(CI);
+  bool isCallingConvC = CI->getCallingConv() == llvm::CallingConv::C;
+
+  // Command-line parameter overrides function attribute.
+  if (EnableUnsafeFPShrink.getNumOccurrences() > 0)
+    UnsafeFPShrink = EnableUnsafeFPShrink;
+  else if (Callee->hasFnAttribute("unsafe-fp-math")) {
+    // FIXME: This is the same problem as described in optimizeSqrt().
+    // If calls gain access to IR-level FMF, then use that instead of a
+    // function attribute.
+
+    // Check for unsafe-fp-math = true.
+    Attribute Attr = Callee->getFnAttribute("unsafe-fp-math");
+    if (Attr.getValueAsString() == "true")
+      UnsafeFPShrink = true;
+  }
+
+  // First, check for intrinsics.
+  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
+    if (!isCallingConvC)
+      return nullptr;
+    switch (II->getIntrinsicID()) {
+    case Intrinsic::pow:
+      return optimizePow(CI, Builder);
+    case Intrinsic::exp2:
+      return optimizeExp2(CI, Builder);
+    case Intrinsic::fabs:
+      return optimizeFabs(CI, Builder);
+    case Intrinsic::sqrt:
+      return optimizeSqrt(CI, Builder);
+    default:
+      return nullptr;
+    }
+  }
+
+  // Then check for known library functions.
+  if (TLI->getLibFunc(FuncName, Func) && TLI->has(Func)) {
+    // We never change the calling convention.
+    if (!ignoreCallingConv(Func) && !isCallingConvC)
+      return nullptr;
+    if (Value *V = optimizeStringMemoryLibCall(CI, Builder))
+      return V;
+    switch (Func) {
     case LibFunc::cosf:
     case LibFunc::cos:
     case LibFunc::cosl:
-- 
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