From: Reed Kotler <rkotler@mips.com>
Date: Wed, 18 Dec 2013 23:57:48 +0000 (+0000)
Subject: Fix a problem with mips16 stubs when calls are transformed during
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=deb8e33163b237cecb58eacb90168155eee0573f;p=oota-llvm.git

Fix a problem with mips16 stubs when calls are transformed during
tail call optimization. Some more work may be needed for indirect
calls but this patch fixes the current regression in Prolangc++/trees.
S2 optimization as part of the general cleanup and optimization
of prolog and epilog was not saving S2 in this case and needed to.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197630 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/Mips/Mips16HardFloat.cpp b/lib/Target/Mips/Mips16HardFloat.cpp
index 65dbd74a1c8..cb0ea869887 100644
--- a/lib/Target/Mips/Mips16HardFloat.cpp
+++ b/lib/Target/Mips/Mips16HardFloat.cpp
@@ -13,6 +13,7 @@
 
 #define DEBUG_TYPE "mips16-hard-float"
 #include "Mips16HardFloat.h"
+#include "llvm/IR/Value.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -167,6 +168,11 @@ static bool needsFPReturnHelper(Function &F) {
   return whichFPReturnVariant(RetType) != NoFPRet;
 }
 
+static bool needsFPReturnHelper(const FunctionType &FT) {
+  Type* RetType = FT.getReturnType();
+  return whichFPReturnVariant(RetType) != NoFPRet;
+}
+
 static bool needsFPHelperFromSig(Function &F) {
   return needsFPStubFromParams(F) || needsFPReturnHelper(F);
 }
@@ -400,7 +406,19 @@ static bool fixupFPReturnAndCall
         Value *F = (M->getOrInsertFunction(Name, A, MyVoid, T, NULL));
         CallInst::Create(F, Params, "", &Inst );
       } else if (const CallInst *CI = dyn_cast<CallInst>(I)) {
+          const Value* V = CI->getCalledValue();
+          const Type* T = 0;
+          if (V) T = V->getType();
+          const PointerType *PFT=0;
+          if (T) PFT = dyn_cast<PointerType>(T);
+          const FunctionType *FT=0;
+          if (PFT) FT = dyn_cast<FunctionType>(PFT->getElementType());
           Function *F_ =  CI->getCalledFunction();
+          if (FT && needsFPReturnHelper(*FT) &&
+              !(F_ && isIntrinsicInline(F_))) {
+            Modified=true;
+            F.addFnAttr("saveS2");
+          }
           if (F_ && !isIntrinsicInline(F_)) {
           // pic mode calls are handled by already defined
           // helper functions
diff --git a/test/CodeGen/Mips/tail16.ll b/test/CodeGen/Mips/tail16.ll
new file mode 100644
index 00000000000..4e62e557478
--- /dev/null
+++ b/test/CodeGen/Mips/tail16.ll
@@ -0,0 +1,20 @@
+; RUN: llc -mtriple=mipsel-linux-gnu -march=mipsel -mcpu=mips16 -soft-float -mips16-hard-float -relocation-model=pic   < %s | FileCheck %s 
+
+; Function Attrs: nounwind optsize
+define float @h()  {
+entry:
+  %call = tail call float bitcast (float (...)* @g to float ()*)() 
+  ret float %call
+; CHECK:	.ent	h
+; CHECK: 	save	$16, $ra, $18, 32
+; CHECK: 	lw	${{[0-9]+}}, %got(__mips16_call_stub_sf_0)(${{[0-9]+}})
+; CHECK: 	restore	$16, $ra, $18, 32
+; CHECK: 	.end	h
+}
+
+; Function Attrs: optsize
+declare float @g(...) 
+
+
+
+