[ARM] Use correct half-precision functions in EABI mode

[olista01]

Summary

The ARM RTABI defines the half- to single-precision float conversion functions with an aeabi prefix, but libgcc only has them with a gnu prefix. Therefore we need to emit the aeabi version when compiling with an eabi or eabihf triple, and the gnu version with a gnueabi or gnueabihf triple.

[ab]

Do these need aliases in compiler-rt?

[rengolin]

In D12733#242508, @ab wrote:

Do these need aliases in compiler-rt?

Yes, we don't have the eabi versions in RT yet.

[ab]

Renato: Alright then, this mostly LGTM, but what do I know about ARM ABIs! I'll let you have the final say.

Oliver: please make sure to commit the compiler-rt additions first.

lib/Target/ARM/ARMISelLowering.cpp

402–403

The same thing is done for f64->f16 when Subtarget->isAAPCS_ABI(), not isTargetAEABI(). Should we also set the f64 libcall here?

I don't think any runtime has a f16->f64 libcall though.

test/CodeGen/ARM/fp16.ll

16–17

What about adding a common shared prefix, say --check-prefix=CHECK-ALL or =CHECK, to simplify the -LABELs ?

[rengolin]

In D12733#243549, @ab wrote:

Renato: Alright then, this mostly LGTM, but what do I know about ARM ABIs! I'll let you have the final say.

Looks ok to me too, with your comments.

Oliver: please make sure to commit the compiler-rt additions first.

Sounds like a good plan.

Thanks!

lib/Target/ARM/ARMISelLowering.cpp

402–403

Good point, I think we should.

test/CodeGen/ARM/fp16.ll

16–17

Yes, you can use CHECK-LABEL for all of them.

[olista01]

Compiler-rt change up for review at D13204, sorry for the delay.

[olista01]

Also set the libcall name for FPROUND_F64_F16, and simplify the test.

[olista01]

Thanks, committed as r249565.

lib/Target/ARM/ARMISelLowering.cpp

if (Subtarget->isAAPCS_ABI()) {
     setLibcallCallingConv(RTLIB::FPROUND_F64_F16, CallingConv::ARM_AAPCS);
     setLibcallCallingConv(RTLIB::FPEXT_F16_F32, CallingConv::ARM_AAPCS);
   } else {
     setLibcallCallingConv(RTLIB::FPROUND_F32_F16, CallingConv::ARM_APCS);
     setLibcallCallingConv(RTLIB::FPROUND_F64_F16, CallingConv::ARM_APCS);
     setLibcallCallingConv(RTLIB::FPEXT_F16_F32, CallingConv::ARM_APCS);
   }
 
+  // In EABI, these functions have an __aeabi_ prefix, but in GNUEABI they have
+  // a __gnu_ prefix (which is the default).
+  if (Subtarget->isTargetAEABI()) {
+    setLibcallName(RTLIB::FPROUND_F32_F16, "__aeabi_f2h");
+    setLibcallName(RTLIB::FPROUND_F64_F16, "__aeabi_d2h");
+    setLibcallName(RTLIB::FPEXT_F16_F32,   "__aeabi_h2f");
+  }
+
   if (Subtarget->isThumb1Only())
     addRegisterClass(MVT::i32, &ARM::tGPRRegClass);
   else
     addRegisterClass(MVT::i32, &ARM::GPRRegClass);
   if (!Subtarget->useSoftFloat() && Subtarget->hasVFP2() &&
       !Subtarget->isThumb1Only()) {
     addRegisterClass(MVT::f32, &ARM::SPRRegClass);
     addRegisterClass(MVT::f64, &ARM::DPRRegClass);

test/CodeGen/ARM/fp16.ll

-; RUN: llc < %s | FileCheck %s
-; RUN: llc -mattr=+vfp3,+fp16 < %s | FileCheck --check-prefix=CHECK-FP16 %s
-; RUN: llc -mtriple=armv8-eabihf < %s | FileCheck --check-prefix=CHECK-ARMV8 %s
-; RUN: llc -mtriple=thumbv7m-eabi < %s | FileCheck --check-prefix=CHECK-SOFTFLOAT %s
+; RUN: llc -mtriple=armv7a--none-eabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-HARDFLOAT-EABI %s
+; RUN: llc -mtriple=armv7a--none-gnueabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-HARDFLOAT-GNU %s
+; RUN: llc -mattr=+vfp3,+fp16 < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-FP16 %s
+; RUN: llc -mtriple=armv8-eabihf < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-ARMV8 %s
+; RUN: llc -mtriple=thumbv7m-eabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-SOFTFLOAT-EABI %s
+; RUN: llc -mtriple=thumbv7m-gnueabi < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-SOFTFLOAT-GNU %s
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n32"
 target triple = "armv7---eabihf"
 
 @x = global i16 12902
 @y = global i16 0
 @z = common global i16 0
 
 define void @foo() nounwind {
 ; CHECK-LABEL: foo:
-; CHECK-FP16-LABEL: foo:
-; CHECK-ARMV8-LABEL: foo:
-; CHECK-SOFTFLOAT-LABEL: foo:
 entry:
   %0 = load i16, i16* @x, align 2
   %1 = load i16, i16* @y, align 2
   %2 = tail call float @llvm.convert.from.fp16.f32(i16 %0)
-; CHECK: __gnu_h2f_ieee
+; CHECK-HARDFLOAT-EABI: __aeabi_h2f
+; CHECK-HARDFLOAT-GNU: __gnu_h2f_ieee
 ; CHECK-FP16: vcvtb.f32.f16
 ; CHECK-ARMv8: vcvtb.f32.f16
-; CHECK-SOFTFLOAT: __gnu_h2f_ieee
+; CHECK-SOFTFLOAT-EABI: __aeabi_h2f
+; CHECK-SOFTFLOAT-GNU: __gnu_h2f_ieee
   %3 = tail call float @llvm.convert.from.fp16.f32(i16 %1)
-; CHECK: __gnu_h2f_ieee
+; CHECK-HARDFLOAT-EABI: __aeabi_h2f
+; CHECK-HARDFLOAT-GNU: __gnu_h2f_ieee
 ; CHECK-FP16: vcvtb.f32.f16
 ; CHECK-ARMV8: vcvtb.f32.f16
-; CHECK-SOFTFLOAT: __gnu_h2f_ieee
+; CHECK-SOFTFLOAT-EABI: __aeabi_h2f
+; CHECK-SOFTFLOAT-GNU: __gnu_h2f_ieee
   %4 = fadd float %2, %3
   %5 = tail call i16 @llvm.convert.to.fp16.f32(float %4)
-; CHECK: __gnu_f2h_ieee
+; CHECK-HARDFLOAT-EABI: __aeabi_f2h
+; CHECK-HARDFLOAT-GNU: __gnu_f2h_ieee
 ; CHECK-FP16: vcvtb.f16.f32
 ; CHECK-ARMV8: vcvtb.f16.f32
-; CHECK-SOFTFLOAT: __gnu_f2h_ieee
+; CHECK-SOFTFLOAT-EABI: __aeabi_f2h
+; CHECK-SOFTFLOAT-GNU: __gnu_f2h_ieee
   store i16 %5, i16* @x, align 2
   ret void
 }
 
 define double @test_from_fp16(i16 %in) {
 ; CHECK-LABEL: test_from_fp16:
-; CHECK-FP16-LABEL: test_from_fp16:
-; CHECK-ARMV8-LABEL: test_from_fp16:
-; CHECK-SOFTFLOAT-LABEL: test_from_fp16:
   %val = call double @llvm.convert.from.fp16.f64(i16 %in)
-; CHECK: bl __gnu_h2f_ieee
-; CHECK: vmov [[TMP:s[0-9]+]], r0
-; CHECK: vcvt.f64.f32 d0, [[TMP]]
+; CHECK-HARDFLOAT-EABI: bl __aeabi_h2f
+; CHECK-HARDFLOAT-EABI: vmov [[TMP:s[0-9]+]], r0
+; CHECK-HARDFLOAT-EABI: vcvt.f64.f32 {{d[0-9]+}}, [[TMP]]
+
+; CHECK-HARDFLOAT-GNU: bl __gnu_h2f_ieee
+; CHECK-HARDFLOAT-GNU: vmov [[TMP:s[0-9]+]], r0
+; CHECK-HARDFLOAT-GNU: vcvt.f64.f32 {{d[0-9]+}}, [[TMP]]
 
 ; CHECK-FP16: vmov [[TMP16:s[0-9]+]], r0
 ; CHECK-FP16: vcvtb.f32.f16 [[TMP32:s[0-9]+]], [[TMP16]]
 ; CHECK-FP16: vcvt.f64.f32 d0, [[TMP32]]
 
 ; CHECK-ARMV8: vmov [[TMP:s[0-9]+]], r0
 ; CHECK-ARMV8: vcvtb.f64.f16 d0, [[TMP]]
 
-; CHECK-SOFTFLOAT: bl __gnu_h2f_ieee
-; CHECK-SOFTFLOAT: bl __aeabi_f2d
+; CHECK-SOFTFLOAT-EABI: bl __aeabi_h2f
+; CHECK-SOFTFLOAT-EABI: bl __aeabi_f2d
+
+; CHECK-SOFTFLOAT-GNU: bl __gnu_h2f_ieee
+; CHECK-SOFTFLOAT-GNU: bl __aeabi_f2d
   ret double %val
 }
 
 define i16 @test_to_fp16(double %in) {
 ; CHECK-LABEL: test_to_fp16:
-; CHECK-FP16-LABEL: test_to_fp16:
-; CHECK-ARMV8-LABEL: test_to_fp16:
-; CHECK-SOFTFLOAT-LABEL: test_to_fp16:
   %val = call i16 @llvm.convert.to.fp16.f64(double %in)
-; CHECK: bl __aeabi_d2h
+; CHECK-HARDFLOAT-EABI: bl __aeabi_d2h
+
+; CHECK-HARDFLOAT-GNU: bl __aeabi_d2h
 
 ; CHECK-FP16: bl __aeabi_d2h
 
 ; CHECK-ARMV8: vcvtb.f16.f64 [[TMP:s[0-9]+]], d0
 ; CHECK-ARMV8: vmov r0, [[TMP]]
 
-; CHECK-SOFTFLOAT: bl __aeabi_d2h
+; CHECK-SOFTFLOAT-EABI: bl __aeabi_d2h
+
+; CHECK-SOFTFLOAT-GNU: bl __aeabi_d2h
   ret i16 %val
 }
 
 declare float @llvm.convert.from.fp16.f32(i16) nounwind readnone
 declare double @llvm.convert.from.fp16.f64(i16) nounwind readnone
 
 declare i16 @llvm.convert.to.fp16.f32(float) nounwind readnone
 declare i16 @llvm.convert.to.fp16.f64(double) nounwind readnone

test/CodeGen/Thumb2/float-intrinsics-double.ll

 ; FP-ARMv8: vcvt{{[bt]}}.f16.f64
   %1 = call i16 @llvm.convert.to.fp16.f64(double %a)
   ret i16 %1
 }
 
 declare double @llvm.convert.from.fp16.f64(i16 %a)
 define double @h_to_d(i16 %a) {
 ; CHECK-LABEL: h_to_d:
-; NONE: bl __gnu_h2f_ieee
+; NONE: bl __aeabi_h2f
 ; NONE: bl __aeabi_f2d
 ; SP: vcvt{{[bt]}}.f32.f16
 ; SP: bl __aeabi_f2d
 ; VFPv4: vcvt{{[bt]}}.f32.f16
 ; VFPv4: vcvt.f64.f32
 ; FP-ARMv8: vcvt{{[bt]}}.f64.f16
   %1 = call double @llvm.convert.from.fp16.f64(i16 %a)
   ret double %1
 }

test/CodeGen/Thumb2/float-intrinsics-float.ll

 ; NO-VMLA: vadd.f32
   %1 = call float @llvm.fmuladd.f32(float %a, float %b, float %c)
   ret float %1
 }
 
 declare i16 @llvm.convert.to.fp16.f32(float %a)
 define i16 @f_to_h(float %a) {
 ; CHECK-LABEL: f_to_h:
-; SOFT: bl __gnu_f2h_ieee
+; SOFT: bl __aeabi_f2h
 ; HARD: vcvt{{[bt]}}.f16.f32
   %1 = call i16 @llvm.convert.to.fp16.f32(float %a)
   ret i16 %1
 }
 
 declare float @llvm.convert.from.fp16.f32(i16 %a)
 define float @h_to_f(i16 %a) {
 ; CHECK-LABEL: h_to_f:
-; SOFT: bl __gnu_h2f_ieee
+; SOFT: bl __aeabi_h2f
 ; HARD: vcvt{{[bt]}}.f32.f16
   %1 = call float @llvm.convert.from.fp16.f32(i16 %a)
   ret float %1
 }