Fix the encoding of the armv7m (MClass) for MSR APSR writes which was missing

the 0b10 mask encoding bits.  Make MSR APSR writes without a _<bits> qualifier
an alias for MSR APSR_nzcvq even though ARM as deprecated it use.  Also add
support for suffixes (_nzcvq, _g, _nzcvqg) for APSR versions.  Some FIXMEs in
the code for better error checking when versions shouldn't be used.
rdar://11457025

llvm-svn: 157019

1 files changed, 29 insertions, 4 deletions

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 88659796705..00e7f6e8fb9 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -3324,10 +3324,35 @@ parseMSRMaskOperand(SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
     // See ARMv6-M 10.1.1
     std::string Name = Mask.lower();
     unsigned FlagsVal = StringSwitch<unsigned>(Name)
-      .Case("apsr", 0)
-      .Case("iapsr", 1)
-      .Case("eapsr", 2)
-      .Case("xpsr", 3)
+      // Note: in the documentation:
+      //  ARM deprecates using MSR APSR without a _<bits> qualifier as an alias
+      //  for MSR APSR_nzcvq.
+      // but we do make it an alias here.  This is so to get the "mask encoding"
+      // bits correct on MSR APSR writes.
+      //
+      // FIXME: Note the 0xc00 "mask encoding" bits version of the registers
+      // should really only be allowed when writing a special register.  Note
+      // they get dropped in the MRS instruction reading a special register as
+      // the SYSm field is only 8 bits.
+      //
+      // FIXME: the _g and _nzcvqg versions are only allowed if the processor
+      // includes the DSP extension but that is not checked.
+      .Case("apsr", 0x800)
+      .Case("apsr_nzcvq", 0x800)
+      .Case("apsr_g", 0x400)
+      .Case("apsr_nzcvqg", 0xc00)
+      .Case("iapsr", 0x801)
+      .Case("iapsr_nzcvq", 0x801)
+      .Case("iapsr_g", 0x401)
+      .Case("iapsr_nzcvqg", 0xc01)
+      .Case("eapsr", 0x802)
+      .Case("eapsr_nzcvq", 0x802)
+      .Case("eapsr_g", 0x402)
+      .Case("eapsr_nzcvqg", 0xc02)
+      .Case("xpsr", 0x803)
+      .Case("xpsr_nzcvq", 0x803)
+      .Case("xpsr_g", 0x403)
+      .Case("xpsr_nzcvqg", 0xc03)
       .Case("ipsr", 5)
       .Case("epsr", 6)
       .Case("iepsr", 7)