emitIAS for fld and fstp

src/IceInstX8632.cpp

Index: src/IceInstX8632.cpp
diff --git a/src/IceInstX8632.cpp b/src/IceInstX8632.cpp
index e2d39c3ea4b30905e61b7744cf5cb1d065fad131..a783149c0204e4af7654164d08d78159c73afa1f 100644
--- a/src/IceInstX8632.cpp
+++ b/src/IceInstX8632.cpp
@@ -1831,7 +1831,8 @@ template <> void InstX8632MovssRegs::emitIAS(const Cfg *Func) const {
   assert(Dest->hasReg() && Src->hasReg());
   x86::AssemblerX86 *Asm = Func->getAssembler<x86::AssemblerX86>();
   intptr_t StartPosition = Asm->GetPosition();
-  Asm->movss(RegX8632::getEncodedXmm(Dest->getRegNum()),
+  Asm->movss(IceType_f32,
+             RegX8632::getEncodedXmm(Dest->getRegNum()),
              RegX8632::getEncodedXmm(Src->getRegNum()));
   Ostream &Str = Func->getContext()->getStrEmit();
   emitIASBytes(Str, Asm, StartPosition);
@@ -1918,6 +1919,38 @@ void InstX8632Fld::emit(const Cfg *Func) const {
   Str << "\n";
 }
 
+void InstX8632Fld::emitIAS(const Cfg *Func) const {
+  x86::AssemblerX86 *Asm = Func->getAssembler<x86::AssemblerX86>();
+  intptr_t StartPosition = Asm->GetPosition();
+  assert(getSrcSize() == 1);
+  const Operand *Src = getSrc(0);
+  Type Ty = Src->getType();
+  if (const auto Var = llvm::dyn_cast<Variable>(Src)) {
+    if (Var->hasReg()) {
+      // This is a physical xmm register, so we need to spill it to a
+      // temporary stack slot.
+      x86::Immediate Width(typeWidthInBytes(Ty));
+      Asm->sub(IceType_i32, RegX8632::Encoded_Reg_esp, Width);
+      x86::Address StackSlot = x86::Address(RegX8632::Encoded_Reg_esp, 0);
+      Asm->movss(Ty, StackSlot, RegX8632::getEncodedXmm(Var->getRegNum()));
+      Asm->fld(Ty, StackSlot);
+      Asm->add(IceType_i32, RegX8632::Encoded_Reg_esp, Width);
+    } else {
+      x86::Address StackAddr(static_cast<TargetX8632 *>(Func->getTarget())
+                                 ->stackVarToAsmOperand(Var));
+      Asm->fld(Ty, StackAddr);
+    }
+  } else if (const auto Mem = llvm::dyn_cast<OperandX8632Mem>(Src)) {
+    Asm->fld(Ty, Mem->toAsmAddress(Asm));
+  } else if (const auto Imm = llvm::dyn_cast<Constant>(Src)) {
+    Asm->fld(Ty, x86::Address::ofConstPool(Func->getContext(), Asm, Imm));
+  } else {
+    llvm_unreachable("Unexpected operand type");
+  }
+  Ostream &Str = Func->getContext()->getStrEmit();
+  emitIASBytes(Str, Asm, StartPosition);
+}
+
 void InstX8632Fld::dump(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrDump();
   Str << "fld." << getSrc(0)->getType() << " ";
@@ -1927,10 +1960,6 @@ void InstX8632Fld::dump(const Cfg *Func) const {
 void InstX8632Fstp::emit(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrEmit();
   assert(getSrcSize() == 0);
-  if (getDest() == NULL) {

[Jim Stichnoth, 2014/10/08 19:09:41]

I think "fstp st(0)" might possibly be used in the future, in the situation that
https://codereview.chromium.org/563303003/ addresses (but addresses in a
different way).

A better way might be to mark the fstp instruction as having side effects, and
allow dead-instruction elimination to "partially" delete the fstp instruction
(or any such instruction) by setting its Dest=NULL.

[jvoung (off chromium), 2014/10/08 20:51:47]

Okay, so the benefit of that is it can avoid allocating a Variable for Dest if
it's unused / avoid conflicts.

I'll add back the check for getDest() == NULL and emit fstp st(0) then, and
leave a note?

[Jim Stichnoth, 2014/10/08 21:10:28]

Yes, thanks!

-    Str << "\tfstp\tst(0)\n";
-    return;
-  }
   if (!getDest()->hasReg()) {
     Str << "\tfstp\t";
     getDest()->emit(Func);
@@ -1951,6 +1980,32 @@ void InstX8632Fstp::emit(const Cfg *Func) const {
   Str << "\tadd\tesp, " << Width << "\n";
 }
 
+void InstX8632Fstp::emitIAS(const Cfg *Func) const {
+  x86::AssemblerX86 *Asm = Func->getAssembler<x86::AssemblerX86>();
+  intptr_t StartPosition = Asm->GetPosition();
+  assert(getSrcSize() == 0);
+  const Variable *Dest = getDest();
+  Type Ty = Dest->getType();
+  if (!Dest->hasReg()) {
+    x86::Address StackAddr(static_cast<TargetX8632 *>(Func->getTarget())
+                                 ->stackVarToAsmOperand(Dest));
+    Asm->fstp(Ty, StackAddr);
+  } else {
+    // Dest is a physical (xmm) register, so st(0) needs to go through
+    // memory.  Hack this by creating a temporary stack slot, spilling
+    // st(0) there, loading it into the xmm register, and deallocating
+    // the stack slot.
+    x86::Immediate Width(typeWidthInBytes(Ty));
+    Asm->sub(IceType_i32, RegX8632::Encoded_Reg_esp, Width);
+    x86::Address StackSlot = x86::Address(RegX8632::Encoded_Reg_esp, 0);
+    Asm->fstp(Ty, StackSlot);
+    Asm->movss(Ty, RegX8632::getEncodedXmm(Dest->getRegNum()), StackSlot);
+    Asm->add(IceType_i32, RegX8632::Encoded_Reg_esp, Width);
+  }
+  Ostream &Str = Func->getContext()->getStrEmit();
+  emitIASBytes(Str, Asm, StartPosition);
+}
+
 void InstX8632Fstp::dump(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrDump();
   dumpDest(Func);