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>

llvm-svn: 161232

2 files changed, 18 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index e5ea6e693f8..635752ab65f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/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() {}
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 287c679f975..4e5e3bae62c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -979,7 +979,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
   // Initialize the Fast-ISel state, if needed.
   FastISel *FastIS = 0;
   if (TM.Options.EnableFastISel)
-    FastIS = TLI.createFastISel(*FuncInfo);
+    FastIS = TLI.createFastISel(*FuncInfo, LibInfo);
 
   // Iterate over all basic blocks in the function.
   ReversePostOrderTraversal<const Function*> RPOT(&Fn);