[ARM] Honor FeatureD16 in the assembler and disassembler

Some ARM FPUs only have 16 double-precision registers, rather than the
normal 32. LLVM represents this with the D16 target feature. This is
currently used by CodeGen to avoid using high registers when they are
not available, but the assembler and disassembler do not.

I fix this in the assmebler and disassembler rather than the
InstrInfo.td files, as the latter would require a large number of
changes everywhere one of the floating-point instructions is referenced
in the backend. This solution is similar to the one used for
co-processor numbers and MSR masks.

llvm-svn: 221341

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/test/MC/Disassembler/ARM/d16.txt b/llvm/test/MC/Disassembler/ARM/d16.txt
new file mode 100644
index 00000000000..42560e19b39
--- /dev/null
+++ b/llvm/test/MC/Disassembler/ARM/d16.txt
@@ -0,0 +1,23 @@
+# RUN: llvm-mc < %s -triple thumbv7-unknown-unknown -disassemble -mattr=+vfp4,-d16 |& FileCheck %s --check-prefix=D32
+# RUN: llvm-mc < %s -triple thumbv7-unknown-unknown -disassemble -mattr=+vfp4,-d16 |& FileCheck %s --check-prefix=D32
+
+
+# D32: vadd.f64 d1, d2, d16
+# D16: warning: invalid instruction encoding
+[0x32,0xee,0x20,0x1b]
+
+# D32: vadd.f64 d1, d17, d6
+# D16: warning: invalid instruction encoding
+[0x31,0xee,0x86,0x1b]
+
+# D32: vadd.f64 d19, d7, d6
+# D16: warning: invalid instruction encoding
+[0x77,0xee,0x06,0x3b]
+
+# D32: vcvt.f64.f32 d22, s4
+# D16: warning: invalid instruction encoding
+[0xf7,0xee,0xc2,0x6a]
+
+# D32: vcvt.f32.f64 s26, d30
+# D16: warning: invalid instruction encoding
+[0xb7,0xee,0xee,0xdb]