Implements int2fp, fp2int, and fp2fp conversions for ARM32.

src/IceTargetLoweringARM32.cpp

 //===- subzero/src/IceTargetLoweringARM32.cpp - ARM32 lowering ------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 16 matching lines @@
 #include "IcePhiLoweringImpl.h"
 #include "IceRegistersARM32.h"
 #include "IceTargetLoweringARM32.def"
 #include "IceUtils.h"
 #include "llvm/Support/MathExtras.h"
 
 namespace Ice {
 
 namespace {
 
-void UnimplementedError(const ClFlags &Flags) {
-  if (!Flags.getSkipUnimplemented()) {
-    // Use llvm_unreachable instead of report_fatal_error, which gives better
-    // stack traces.
-    llvm_unreachable("Not yet implemented");
-    abort();
-  }
-}
+// UnimplementedError is defined as a macro so that we can get actual line
+// numbers.
+#define UnimplementedError(Flags)                                              \
+  do {                                                                         \
+    if (!static_cast<const ClFlags &>(Flags).getSkipUnimplemented()) {         \
+      /* Use llvm_unreachable instead of report_fatal_error, which gives       \
+         better                                                                \
+         stack traces. */                                                      \

[ascull, 2015/09/10 16:44:09]

reflow

[John, 2015/09/11 12:16:48]

Done.

+      llvm_unreachable("Not yet implemented");                                 \
+      abort();                                                                 \
+    }                                                                          \
+  } while (0)
 
 // The following table summarizes the logic for lowering the icmp instruction
 // for i32 and narrower types.  Each icmp condition has a clear mapping to an
 // ARM32 conditional move instruction.
 
 const struct TableIcmp32_ {
   CondARM32::Cond Mapping;
 } TableIcmp32[] = {
 #define X(val, is_signed, swapped64, C_32, C1_64, C2_64)                       \
   { CondARM32::C_32 }                                                          \
@@ skipping 2013 matching lines @@
       // t1 = trunc Src0RF; Dest = t1
       Variable *T = makeReg(Dest->getType());
       _mov(T, Src0RF);
       if (Dest->getType() == IceType_i1)
         _and(T, T, Ctx->getConstantInt1(1));
       _mov(Dest, T);
     }
     break;
   }
   case InstCast::Fptrunc:
-    UnimplementedError(Func->getContext()->getFlags());
-    break;
   case InstCast::Fpext: {
-    UnimplementedError(Func->getContext()->getFlags());
+    // fptrunc: dest.f32 = fptrunc src0.fp64
+    // fpext: dest.f64 = fptrunc src0.fp32
+    const bool IsTrunc = CastKind == InstCast::Fptrunc;
+    if (isVectorType(Dest->getType())) {
+      UnimplementedError(Func->getContext()->getFlags());
+      break;
+    }
+    assert(Dest->getType() == (IsTrunc ? IceType_f32 : IceType_f64));
+    assert(Src0->getType() == (IsTrunc ? IceType_f64 : IceType_f32));
+    Variable *Src0R = legalizeToReg(Src0);
+    Variable *T = makeReg(Dest->getType());
+    _vcvt(T, Src0R, IsTrunc ? InstARM32Vcvt::D2s : InstARM32Vcvt::S2d);
+    _mov(Dest, T);
     break;
   }
   case InstCast::Fptosi:
-    UnimplementedError(Func->getContext()->getFlags());
-    // Add a fake def to keep liveness consistent in the meantime.
-    Context.insert(InstFakeDef::create(Func, Dest));
+  case InstCast::Fptoui: {
+    // fptosi:
+    //     t1.fp = vcvt src0.fp
+    //     t2.i32 = vmov t1.fp
+    //     dest.int = conv t2.i32     @ Truncates the result if needed.
+    // fptoui:
+    //     t1.fp = vcvt src0.fp
+    //     t2.u32 = vmov t1.fp
+    //     dest.uint = conv t2.u32    @ Truncates the result if needed.
+    if (isVectorType(Dest->getType())) {
+      UnimplementedError(Func->getContext()->getFlags());
+      break;
+    } else if (Dest->getType() == IceType_i64) {

[Jim Stichnoth, 2015/09/10 17:17:10]

Make this a separate "if" statement instead of "else if"?

[John, 2015/09/11 12:16:48]

I tend to prefer the looks of

if (Cond1) {
  Body1;
  break/return;
} else if (Cond2) {
  Body2;
  break/return;
}

versus

if (Cond1) {
  Body1;
  break/return;
}
if (Cond2) {
  Body2;
  break/return;
}

Plus, an "else" helps when first looking at the code -- particularly on IDE with
collapsible blocks -- because you know that either Body1 or Body2 will run
(never both) even before you look at the code.

It may seem I have a strong opinion on the matter, but I really don't -- I was
just justifying my choice. Done.

[Jim Stichnoth, 2015/09/11 13:49:40]

I brought it up because LLVM seems to opine pretty strongly on the matter.
http://llvm.org/docs/CodingStandards.html#don-t-use-else-after-a-return

+      UnimplementedError(Func->getContext()->getFlags());
+      break;
+    }
+    const bool DestIsSigned = CastKind == InstCast::Fptosi;
+    Variable *Src0R = legalizeToReg(Src0);
+    Variable *T_fp = makeReg(IceType_f32);
+    if (isFloat32Asserting32Or64(Src0->getType())) {
+      _vcvt(T_fp, Src0R,
+            DestIsSigned ? InstARM32Vcvt::S2si : InstARM32Vcvt::S2ui);
+    } else {
+      _vcvt(T_fp, Src0R,
+            DestIsSigned ? InstARM32Vcvt::D2si : InstARM32Vcvt::D2ui);
+    }
+    Variable *T = makeReg(IceType_i32);
+    _vmov(T, T_fp);
+    if (Dest->getType() != IceType_i32) {
+      Variable *T_1 = makeReg(Dest->getType());
+      lowerCast(InstCast::create(Func, InstCast::Trunc, T_1, T));
+      T = T_1;
+    }
+    _mov(Dest, T);
     break;
-  case InstCast::Fptoui:
-    UnimplementedError(Func->getContext()->getFlags());
-    break;
+  }
   case InstCast::Sitofp:
-    UnimplementedError(Func->getContext()->getFlags());
-    break;
   case InstCast::Uitofp: {
-    UnimplementedError(Func->getContext()->getFlags());
+    // sitofp:
+    //     t1.i32 = sext src.int    @ sign-extends src0 if needed.
+    //     t2.fp32 = vmov t1.i32
+    //     t3.fp = vcvt.{fp}.s32    @ fp is either f32 or f64
+    // uitofp:
+    //     t1.i32 = zext src.int    @ zero-extends src0 if needed.
+    //     t2.fp32 = vmov t1.i32
+    //     t3.fp = vcvt.{fp}.s32    @ fp is either f32 or f64
+    if (isVectorType(Dest->getType())) {
+      UnimplementedError(Func->getContext()->getFlags());
+      break;
+    } else if (Src0->getType() == IceType_i64) {
+      UnimplementedError(Func->getContext()->getFlags());
+      break;
+    }
+    const bool SourceIsSigned = CastKind == InstCast::Sitofp;
+    if (Src0->getType() != IceType_i32) {
+      Variable *Src0R_32 = makeReg(IceType_i32);
+      lowerCast(InstCast::create(Func, SourceIsSigned ? InstCast::Sext
+                                                      : InstCast::Zext,
+                                 Src0R_32, Src0));
+      Src0 = Src0R_32;
+    }
+    Variable *Src0R = legalizeToReg(Src0);
+    Variable *Src0R_f32 = makeReg(IceType_f32);
+    _vmov(Src0R_f32, Src0R);
+    Src0R = Src0R_f32;
+    Variable *T = makeReg(Dest->getType());
+    if (isFloat32Asserting32Or64(Dest->getType())) {
+      _vcvt(T, Src0R,
+            SourceIsSigned ? InstARM32Vcvt::Si2s : InstARM32Vcvt::Ui2s);
+    } else {
+      _vcvt(T, Src0R,
+            SourceIsSigned ? InstARM32Vcvt::Si2d : InstARM32Vcvt::Ui2d);
+    }
+    _mov(Dest, T);
     break;
   }
   case InstCast::Bitcast: {
     Operand *Src0 = Inst->getSrc(0);
     if (Dest->getType() == Src0->getType()) {
       InstAssign *Assign = InstAssign::create(Func, Dest, Src0);
       lowerAssign(Assign);
       return;
     }
     UnimplementedError(Func->getContext()->getFlags());
@@ skipping 947 matching lines @@
       << ".eabi_attribute 68, 1   @ Tag_Virtualization_use\n";
   if (CPUFeatures.hasFeature(TargetARM32Features::HWDivArm)) {
     Str << ".eabi_attribute 44, 2   @ Tag_DIV_use\n";
   }
   // Technically R9 is used for TLS with Sandboxing, and we reserve it.
   // However, for compatibility with current NaCl LLVM, don't claim that.
   Str << ".eabi_attribute 14, 3   @ Tag_ABI_PCS_R9_use: Not used\n";
 }
 
 } // end of namespace Ice