Fall back to selection DAG isel for calls to builtin functions.

Fast isel doesn't currently have support for translating builtin function
calls to target instructions.  For embedded environments where the library
functions are not available, this is a matter of correctness and not
just optimization.  Most of this patch is just arranging to make the
TargetLibraryInfo available in fast isel.  <rdar://problem/12008746>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161232 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 2 deletions

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index e5ea6e693f..635752ab65 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -55,6 +55,7 @@
 #include "llvm/Analysis/Loads.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -789,6 +790,18 @@ FastISel::SelectInstruction(const Instruction *I) {
 
   MachineBasicBlock::iterator SavedInsertPt = FuncInfo.InsertPt;
 
+  // As a special case, don't even try to handle calls to builtin library
+  // functions so that calls to builtin functions get translated to
+  // instructions when supported by the target.
+  if (const CallInst *Call = dyn_cast<CallInst>(I)) {
+    const Function *F = Call->getCalledFunction();
+    LibFunc::Func Func;
+    if (F && !F->hasLocalLinkage() && F->hasName() &&
+        LibInfo->getLibFunc(F->getName(), Func) &&
+        LibInfo->has(Func))
+      return false;
+  }
+
   // First, try doing target-independent selection.
   if (SelectOperator(I, I->getOpcode())) {
     ++NumFastIselSuccessIndependent;
@@ -1040,7 +1053,8 @@ FastISel::SelectOperator(const User *I, unsigned Opcode) {
   }
 }
 
-FastISel::FastISel(FunctionLoweringInfo &funcInfo)
+FastISel::FastISel(FunctionLoweringInfo &funcInfo,
+                   const TargetLibraryInfo *libInfo)
   : FuncInfo(funcInfo),
     MRI(FuncInfo.MF->getRegInfo()),
     MFI(*FuncInfo.MF->getFrameInfo()),
@@ -1049,7 +1063,8 @@ FastISel::FastISel(FunctionLoweringInfo &funcInfo)
     TD(*TM.getTargetData()),
     TII(*TM.getInstrInfo()),
     TLI(*TM.getTargetLowering()),
-    TRI(*TM.getRegisterInfo()) {
+    TRI(*TM.getRegisterInfo()),
+    LibInfo(libInfo) {
 }
 
 FastISel::~FastISel() {}