From 3762046dbfbf17b0c21804cce39f02b2dce05ff9 Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Tue, 19 Apr 2011 17:22:22 +0000
Subject: [PATCH] Add support for FastISel'ing varargs calls.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129765 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86FastISel.cpp       | 25 +++++++++++++++++++++----
 test/CodeGen/X86/fast-isel-x86-64.ll | 19 +++++++++++++++++++
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index f4a26923b33..33e7ea5f80e 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -1508,14 +1508,17 @@ bool X86FastISel::X86SelectCall(const Instruction *I) {
   if (CC == CallingConv::Fast && GuaranteedTailCallOpt)
     return false;
 
-  // Let SDISel handle vararg functions.
   const PointerType *PT = cast<PointerType>(CS.getCalledValue()->getType());
   const FunctionType *FTy = cast<FunctionType>(PT->getElementType());
-  if (FTy->isVarArg())
+  bool isVarArg = FTy->isVarArg();
+
+  // Don't know how to handle Win64 varargs yet.  Nothing special needed for
+  // x86-32.  Special handling for x86-64 is implemented.
+  if (isVarArg && Subtarget->isTargetWin64())
     return false;
 
   // Fast-isel doesn't know about callee-pop yet.
-  if (Subtarget->IsCalleePop(FTy->isVarArg(), CC))
+  if (Subtarget->IsCalleePop(isVarArg, CC))
     return false;
 
   // Handle *simple* calls for now.
@@ -1623,7 +1626,7 @@ bool X86FastISel::X86SelectCall(const Instruction *I) {
 
   // Analyze operands of the call, assigning locations to each operand.
   SmallVector<CCValAssign, 16> ArgLocs;
-  CCState CCInfo(CC, false, TM, ArgLocs, I->getParent()->getContext());
+  CCState CCInfo(CC, isVarArg, TM, ArgLocs, I->getParent()->getContext());
 
   // Allocate shadow area for Win64
   if (Subtarget->isTargetWin64())
@@ -1721,6 +1724,17 @@ bool X86FastISel::X86SelectCall(const Instruction *I) {
             X86::EBX).addReg(Base);
   }
 
+  if (Subtarget->is64Bit() && isVarArg && !Subtarget->isTargetWin64()) {
+    // Count the number of XMM registers allocated.
+    static const unsigned XMMArgRegs[] = {
+      X86::XMM0, X86::XMM1, X86::XMM2, X86::XMM3,
+      X86::XMM4, X86::XMM5, X86::XMM6, X86::XMM7
+    };
+    unsigned NumXMMRegs = CCInfo.getFirstUnallocated(XMMArgRegs, 8);
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(X86::MOV8ri),
+            X86::AL).addImm(NumXMMRegs);
+  }
+
   // Issue the call.
   MachineInstrBuilder MIB;
   if (CalleeOp) {
@@ -1775,6 +1789,9 @@ bool X86FastISel::X86SelectCall(const Instruction *I) {
   if (Subtarget->isPICStyleGOT())
     MIB.addReg(X86::EBX);
 
+  if (Subtarget->is64Bit() && isVarArg && !Subtarget->isTargetWin64())
+    MIB.addReg(X86::AL);
+
   // Add implicit physical register uses to the call.
   for (unsigned i = 0, e = RegArgs.size(); i != e; ++i)
     MIB.addReg(RegArgs[i]);
diff --git a/test/CodeGen/X86/fast-isel-x86-64.ll b/test/CodeGen/X86/fast-isel-x86-64.ll
index 1770e732230..46659892983 100644
--- a/test/CodeGen/X86/fast-isel-x86-64.ll
+++ b/test/CodeGen/X86/fast-isel-x86-64.ll
@@ -181,3 +181,22 @@ define void @test15(i8* %a, i8* %b) nounwind {
 ; CHECK-NEXT: movl	%eax, (%rdi)
 ; CHECK-NEXT: ret
 }
+
+; Handling for varargs calls
+declare void @test16callee(...) nounwind
+define void @test16() nounwind {
+; CHECK: test16:
+; CHECK: movl $1, %edi
+; CHECK: movb $0, %al
+; CHECK: callq _test16callee
+  call void (...)* @test16callee(i32 1)
+  br label %block2
+
+block2:
+; CHECK: movabsq $1
+; CHECK: cvtsi2sdq {{.*}} %xmm0
+; CHECK: movb $1, %al
+; CHECK: callq _test16callee
+  call void (...)* @test16callee(double 1.000000e+00)
+  ret void
+}