Emit Tag_ABI_FP_16bit_format build attribute.

The __fp16 type is unconditionally exposed. Since -mfp16-format is not yet
supported, there is not a user switch to change this behaviour. This build
attribute should capture the default behaviour of the compiler, which is to
expose the IEEE 754 version of __fp16.

When -mfp16-format is emitted, that will be the way to control the value of
this build attribute.

Change-Id: I8a46641ff0fd2ef8ad0af5f482a6d1af2ac3f6b0

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224115 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/ARMBuildAttributes.h

@@ -200,6 +200,9 @@ enum {
   // Tag_FP_HP_extension, (=36), uleb128
   AllowHPFP = 1, // Allow use of Half Precision FP
 
+  // Tag_FP_16bit_format, (=38), uleb128
+  FP16FormatIEEE = 1,
+
   // Tag_MPextension_use, (=42), uleb128
   AllowMP = 1, // Allow use of MP extensions
 

lib/Target/ARM/ARMAsmPrinter.cpp

@@ -782,6 +782,13 @@ void ARMAsmPrinter::emitAttributes() {
   if (Subtarget->hasFP16())
       ATS.emitAttribute(ARMBuildAttrs::FP_HP_extension, ARMBuildAttrs::AllowHPFP);
 
+  // FIXME: To support emitting this build attribute as GCC does, the
+  // -mfp16-format option and associated plumbing must be
+  // supported. For now the __fp16 type is exposed by default, so this
+  // attribute should be emitted with value 1.
+  ATS.emitAttribute(ARMBuildAttrs::ABI_FP_16bit_format,
+                    ARMBuildAttrs::FP16FormatIEEE);
+
   if (Subtarget->hasMPExtension())
       ATS.emitAttribute(ARMBuildAttrs::MPextension_use, ARMBuildAttrs::AllowMP);
 

test/CodeGen/ARM/build-attributes.ll

@@ -148,6 +148,7 @@
 ; V6-NOT:   .eabi_attribute 27
 ; V6-NOT:   .eabi_attribute 28
 ; V6-NOT:    .eabi_attribute 36
+; V6:    .eabi_attribute 38, 1
 ; V6-NOT:    .eabi_attribute 42
 ; V6-NOT:    .eabi_attribute 68
 
@@ -178,6 +179,7 @@
 ; V6M-NOT:  .eabi_attribute 27
 ; V6M-NOT:  .eabi_attribute 28
 ; V6M-NOT:  .eabi_attribute 36
+; V6M:  .eabi_attribute 38, 1
 ; V6M-NOT:  .eabi_attribute 42
 ; V6M-NOT:  .eabi_attribute 68
 
@@ -206,6 +208,7 @@
 ; ARM1156T2F-S-NOT: .eabi_attribute 27
 ; ARM1156T2F-S-NOT: .eabi_attribute 28
 ; ARM1156T2F-S-NOT: .eabi_attribute 36
+; ARM1156T2F-S: .eabi_attribute 38, 1
 ; ARM1156T2F-S-NOT:    .eabi_attribute 42
 ; ARM1156T2F-S-NOT:    .eabi_attribute 68
 
@@ -236,6 +239,7 @@
 ; V7M-NOT:  .eabi_attribute 27
 ; V7M-NOT:  .eabi_attribute 28
 ; V7M-NOT:  .eabi_attribute 36
+; V7M:  .eabi_attribute 38, 1
 ; V7M-NOT:  .eabi_attribute 42
 ; V7M-NOT:  .eabi_attribute 44
 ; V7M-NOT:  .eabi_attribute 68
@@ -262,6 +266,7 @@
 ; V7-NOT: .eabi_attribute 27
 ; V7-NOT: .eabi_attribute 28
 ; V7-NOT: .eabi_attribute 36
+; V7: .eabi_attribute 38, 1
 ; V7-NOT:    .eabi_attribute 42
 ; V7-NOT:    .eabi_attribute 68
 
@@ -389,6 +394,11 @@
 ; CORTEX-A7-NOFPU: .eabi_attribute      36, 1
 ; CORTEX-A7-FPUV4: .eabi_attribute      36, 1
 
+; Tag_FP_16bit_format
+; CORTEX-A7-CHECK: .eabi_attribute      38, 1
+; CORTEX-A7-NOFPU: .eabi_attribute      38, 1
+; CORTEX-A7-FPUV4: .eabi_attribute      38, 1
+
 ; Tag_MPextension_use
 ; CORTEX-A7-CHECK: .eabi_attribute      42, 1
 ; CORTEX-A7-NOFPU: .eabi_attribute      42, 1
@@ -496,6 +506,7 @@
 ; CORTEX-A9-SOFT-NOT:  .eabi_attribute 27
 ; CORTEX-A9-SOFT-NOT:  .eabi_attribute 28
 ; CORTEX-A9-SOFT:  .eabi_attribute 36, 1
+; CORTEX-A9-SOFT:  .eabi_attribute 38, 1
 ; CORTEX-A9-SOFT:  .eabi_attribute 42, 1
 ; CORTEX-A9-SOFT:  .eabi_attribute 68, 1
 
@@ -524,6 +535,7 @@
 ; CORTEX-A9-HARD-NOT:  .eabi_attribute 27
 ; CORTEX-A9-HARD:  .eabi_attribute 28, 1
 ; CORTEX-A9-HARD:  .eabi_attribute 36, 1
+; CORTEX-A9-HARD:  .eabi_attribute 38, 1
 ; CORTEX-A9-HARD:  .eabi_attribute 42, 1
 ; CORTEX-A9-HARD:  .eabi_attribute 68, 1
 
@@ -605,6 +617,7 @@
 ; CORTEX-A15-NOT: .eabi_attribute 27
 ; CORTEX-A15-NOT: .eabi_attribute 28
 ; CORTEX-A15: .eabi_attribute 36, 1
+; CORTEX-A15: .eabi_attribute 38, 1
 ; CORTEX-A15: .eabi_attribute 42, 1
 ; CORTEX-A15: .eabi_attribute 44, 2
 ; CORTEX-A15: .eabi_attribute 68, 3
@@ -686,6 +699,7 @@
 ; CORTEX-M0-NOT:  .eabi_attribute 27
 ; CORTEX-M0-NOT:  .eabi_attribute 28
 ; CORTEX-M0-NOT:  .eabi_attribute 36
+; CORTEX-M0:  .eabi_attribute 38, 1
 ; CORTEX-M0-NOT:  .eabi_attribute 42
 ; CORTEX-M0-NOT:  .eabi_attribute 68
 
@@ -716,6 +730,7 @@
 ; CORTEX-M3-NOT:  .eabi_attribute 27
 ; CORTEX-M3-NOT:  .eabi_attribute 28
 ; CORTEX-M3-NOT:  .eabi_attribute 36
+; CORTEX-M3:  .eabi_attribute 38, 1
 ; CORTEX-M3-NOT:  .eabi_attribute 42
 ; CORTEX-M3-NOT:  .eabi_attribute 44
 ; CORTEX-M3-NOT:  .eabi_attribute 68
@@ -746,6 +761,7 @@
 ; CORTEX-M4-SOFT:  .eabi_attribute 27, 1
 ; CORTEX-M4-SOFT-NOT:  .eabi_attribute 28
 ; CORTEX-M4-SOFT:  .eabi_attribute 36, 1
+; CORTEX-M4-SOFT:  .eabi_attribute 38, 1
 ; CORTEX-M4-SOFT-NOT:  .eabi_attribute 42
 ; CORTEX-M4-SOFT-NOT:  .eabi_attribute 44
 ; CORTEX-M4-SOFT-NOT:  .eabi_attribute 68
@@ -775,6 +791,7 @@
 ; CORTEX-M4-HARD:  .eabi_attribute 27, 1
 ; CORTEX-M4-HARD:  .eabi_attribute 28, 1
 ; CORTEX-M4-HARD:  .eabi_attribute 36, 1
+; CORTEX-M4-HARD:  .eabi_attribute 38, 1
 ; CORTEX-M4-HARD-NOT:  .eabi_attribute 42
 ; CORTEX-M4-HARD-NOT:  .eabi_attribute 44
 ; CORTEX-M4-HARD-NOT:  .eabi_attribute 68
@@ -808,6 +825,7 @@
 ; CORTEX-M7-SINGLE:  .eabi_attribute 27, 1
 ; CORTEX-M7-DOUBLE-NOT: .eabi_attribute 27
 ; CORTEX-M7:  .eabi_attribute 36, 1
+; CORTEX-M7:  .eabi_attribute 38, 1
 ; CORTEX-M7:  .eabi_attribute 14, 0
 
 ; CORTEX-M7-NOFPU-FAST-NOT:   .eabi_attribute 19
@@ -838,6 +856,7 @@
 ; CORTEX-R5:  .eabi_attribute 27, 1
 ; CORTEX-R5-NOT:  .eabi_attribute 28
 ; CORTEX-R5-NOT:  .eabi_attribute 36
+; CORTEX-R5:  .eabi_attribute 38, 1
 ; CORTEX-R5-NOT:  .eabi_attribute 42
 ; CORTEX-R5:  .eabi_attribute 44, 2
 ; CORTEX-R5-NOT:  .eabi_attribute 68
@@ -867,6 +886,7 @@
 ; CORTEX-A53-NOT:  .eabi_attribute 27
 ; CORTEX-A53-NOT:  .eabi_attribute 28
 ; CORTEX-A53:  .eabi_attribute 36, 1
+; CORTEX-A53:  .eabi_attribute 38, 1
 ; CORTEX-A53:  .eabi_attribute 42, 1
 ; CORTEX-A53-NOT:  .eabi_attribute 44
 ; CORTEX-A53:  .eabi_attribute 68, 3
@@ -896,6 +916,7 @@
 ; CORTEX-A57-NOT:  .eabi_attribute 27
 ; CORTEX-A57-NOT:  .eabi_attribute 28
 ; CORTEX-A57:  .eabi_attribute 36, 1
+; CORTEX-A57:  .eabi_attribute 38, 1
 ; CORTEX-A57:  .eabi_attribute 42, 1
 ; CORTEX-A57-NOT:  .eabi_attribute 44
 ; CORTEX-A57:  .eabi_attribute 68, 3