[PATCH] starting from ARMv8, rGPR includes SP

[Charlie Turner]

Hi Artyom, thanks for working on this!

Can you use Phabricator in the future, making sure to supply plenty of context? Most people prefer reviewing using that system :)

First patch,

+  case Match_RequiresV8:
+    return Error(IDLoc, "using SP in this instruction requires ARMv8 or later");

I see no test for this diagnostic in patch #1, but I do see a test in patch #2. Is there a good reason why these patches can't be reworked to test what the introduce in the same commit?

+  else if (isThumbOne()) {
+    // Some high-register supporting Thumb1 encodings only allow both registers
+    // to be from r0-r7 when in Thumb2.
+    if (Opc == ARM::tADDhirr && !hasV6MOps() &&
+        isARMLowRegister(Inst.getOperand(1).getReg()) &&
+        isARMLowRegister(Inst.getOperand(2).getReg()))
+      return Match_RequiresThumb2;
+    // Others only require ARMv6 or later.
+    else if (Opc == ARM::tMOVr && !hasV6Ops() &&
+             isARMLowRegister(Inst.getOperand(0).getReg()) &&
+             isARMLowRegister(Inst.getOperand(1).getReg()))
+      return Match_RequiresV6;
+  }

Please try and keep no functional changes like this separate.

As per John's comment, I agree that would be better, but I couldn't figure out how to do that when making the last change to BXJ.
I don't see a better way of doing this selection based on the target. The modelling of unpredictable instructions seems tricky with everything being statically generated as it is.

--Charlie.

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