From 87b51bc2b0e9bced27d6fd95573a3f21691a261c Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 10 Sep 2007 21:15:22 +0000
Subject: [PATCH] 1. Don't call Value::getName(), which is slow. 2. Lower calls
 to fabs and friends to FABS nodes etc unless the function has    internal
 linkage.  Before we wouldn't lower if it had a definition, which    is
 incorrect.  This allows us to compile:

define double @fabs(double %f) {
        %tmp2 = tail call double @fabs( double %f )
        ret double %tmp2
}

into:

_fabs:
        fabs f1, f1
        blr



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41805 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 90 +++++++++++--------
 1 file changed, 52 insertions(+), 38 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index e18beb5018a..60b5290607a 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2969,50 +2969,64 @@ void SelectionDAGLowering::LowerCallTo(Instruction &I,
 void SelectionDAGLowering::visitCall(CallInst &I) {
   const char *RenameFn = 0;
   if (Function *F = I.getCalledFunction()) {
-    if (F->isDeclaration())
+    if (F->isDeclaration()) {
       if (unsigned IID = F->getIntrinsicID()) {
         RenameFn = visitIntrinsicCall(I, IID);
         if (!RenameFn)
           return;
-      } else {    // Not an LLVM intrinsic.
-        const std::string &Name = F->getName();
-        if (Name[0] == 'c' && (Name == "copysign" || Name == "copysignf")) {
-          if (I.getNumOperands() == 3 &&   // Basic sanity checks.
-              I.getOperand(1)->getType()->isFloatingPoint() &&
-              I.getType() == I.getOperand(1)->getType() &&
-              I.getType() == I.getOperand(2)->getType()) {
-            SDOperand LHS = getValue(I.getOperand(1));
-            SDOperand RHS = getValue(I.getOperand(2));
-            setValue(&I, DAG.getNode(ISD::FCOPYSIGN, LHS.getValueType(),
-                                     LHS, RHS));
-            return;
-          }
-        } else if (Name[0] == 'f' && (Name == "fabs" || Name == "fabsf")) {
-          if (I.getNumOperands() == 2 &&   // Basic sanity checks.
-              I.getOperand(1)->getType()->isFloatingPoint() &&
-              I.getType() == I.getOperand(1)->getType()) {
-            SDOperand Tmp = getValue(I.getOperand(1));
-            setValue(&I, DAG.getNode(ISD::FABS, Tmp.getValueType(), Tmp));
-            return;
-          }
-        } else if (Name[0] == 's' && (Name == "sin" || Name == "sinf")) {
-          if (I.getNumOperands() == 2 &&   // Basic sanity checks.
-              I.getOperand(1)->getType()->isFloatingPoint() &&
-              I.getType() == I.getOperand(1)->getType()) {
-            SDOperand Tmp = getValue(I.getOperand(1));
-            setValue(&I, DAG.getNode(ISD::FSIN, Tmp.getValueType(), Tmp));
-            return;
-          }
-        } else if (Name[0] == 'c' && (Name == "cos" || Name == "cosf")) {
-          if (I.getNumOperands() == 2 &&   // Basic sanity checks.
-              I.getOperand(1)->getType()->isFloatingPoint() &&
-              I.getType() == I.getOperand(1)->getType()) {
-            SDOperand Tmp = getValue(I.getOperand(1));
-            setValue(&I, DAG.getNode(ISD::FCOS, Tmp.getValueType(), Tmp));
-            return;
-          }
+      }
+    }
+
+    // Check for well-known libc/libm calls.  If the function is internal, it
+    // can't be a library call.
+    unsigned NameLen = F->getNameLen();
+    if (!F->hasInternalLinkage() && NameLen) {
+      const char *NameStr = F->getNameStart();
+      if (NameStr[0] == 'c' &&
+          ((NameLen == 8 && !strcmp(NameStr, "copysign")) ||
+           (NameLen == 9 && !strcmp(NameStr, "copysignf")))) {
+        if (I.getNumOperands() == 3 &&   // Basic sanity checks.
+            I.getOperand(1)->getType()->isFloatingPoint() &&
+            I.getType() == I.getOperand(1)->getType() &&
+            I.getType() == I.getOperand(2)->getType()) {
+          SDOperand LHS = getValue(I.getOperand(1));
+          SDOperand RHS = getValue(I.getOperand(2));
+          setValue(&I, DAG.getNode(ISD::FCOPYSIGN, LHS.getValueType(),
+                                   LHS, RHS));
+          return;
+        }
+      } else if (NameStr[0] == 'f' &&
+                 ((NameLen == 4 && !strcmp(NameStr, "fabs")) ||
+                  (NameLen == 5 && !strcmp(NameStr, "fabsf")))) {
+        if (I.getNumOperands() == 2 &&   // Basic sanity checks.
+            I.getOperand(1)->getType()->isFloatingPoint() &&
+            I.getType() == I.getOperand(1)->getType()) {
+          SDOperand Tmp = getValue(I.getOperand(1));
+          setValue(&I, DAG.getNode(ISD::FABS, Tmp.getValueType(), Tmp));
+          return;
+        }
+      } else if (NameStr[0] == 's' && 
+                 ((NameLen == 3 && !strcmp(NameStr, "sin")) ||
+                  (NameLen == 4 && !strcmp(NameStr, "sinf")))) {
+        if (I.getNumOperands() == 2 &&   // Basic sanity checks.
+            I.getOperand(1)->getType()->isFloatingPoint() &&
+            I.getType() == I.getOperand(1)->getType()) {
+          SDOperand Tmp = getValue(I.getOperand(1));
+          setValue(&I, DAG.getNode(ISD::FSIN, Tmp.getValueType(), Tmp));
+          return;
+        }
+      } else if (NameStr[0] == 'c' &&
+                 ((NameLen == 3 && !strcmp(NameStr, "cos")) ||
+                  (NameLen == 4 && !strcmp(NameStr, "cosf")))) {
+        if (I.getNumOperands() == 2 &&   // Basic sanity checks.
+            I.getOperand(1)->getType()->isFloatingPoint() &&
+            I.getType() == I.getOperand(1)->getType()) {
+          SDOperand Tmp = getValue(I.getOperand(1));
+          setValue(&I, DAG.getNode(ISD::FCOS, Tmp.getValueType(), Tmp));
+          return;
         }
       }
+    }
   } else if (isa<InlineAsm>(I.getOperand(0))) {
     visitInlineAsm(I);
     return;
-- 
2.34.1