[PATCH] [ARM] SSAT/USAT with an 'asr #32' shift should result in an undefined encoding rather than unpredictable

[Bradley Smith]

When disassembling a SSAT/USAT with an asr #32 shift the disassembler currently returns a SoftFail, this is incorrect since such an instruction encoding is undefined without the DSP extension, (in which case it maps to a different instruction), as such the disassembler should return Fail in this case.

REPOSITORY
  rL LLVM

http://reviews.llvm.org/D7056

Files:
  lib/Target/ARM/Disassembler/ARMDisassembler.cpp
  test/MC/ARM/thumb2-diagnostics.s

Index: lib/Target/ARM/Disassembler/ARMDisassembler.cpp
===================================================================
--- lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -4971,7 +4971,7 @@
   DecodeStatus S = MCDisassembler::Success;
 
   // Shift of "asr #32" is not allowed in Thumb2 mode.
-  if (Val == 0x20) S = MCDisassembler::SoftFail;
+  if (Val == 0x20) S = MCDisassembler::Fail;
   Inst.addOperand(MCOperand::CreateImm(Val));
   return S;
 }
Index: test/MC/ARM/thumb2-diagnostics.s
===================================================================
--- test/MC/ARM/thumb2-diagnostics.s
+++ test/MC/ARM/thumb2-diagnostics.s
@@ -87,4 +87,7 @@
 @ CHECK-ERRORS: error: invalid operand for instruction
 @ CHECK-ERRORS: error: invalid operand for instruction
 
-
+ssat r0, #1, r0, asr #32
+usat r0, #1, r0, asr #32
+@ CHECK-ERRORS: error: 'asr #32' shift amount not allowed in Thumb mode
+@ CHECK-ERRORS: error: 'asr #32' shift amount not allowed in Thumb mode

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