[ARM] Add support for unpredictable MVN instructions.

[yroux]

Summary

This fixes bugzilla 33011
https://bugs.llvm.org/show_bug.cgi?id=33011

Defines bits {19-16} as zero or unpredictable as specified by the ARM ARM in
sections A8.8.116 and A8.8.117.

It fixes also the usage of PC register as destination register for MVN
register-shifted register version as specified in A8.8.117.

Validated with regression testsuite passed without regression.

[yroux]

ping.

[olista01]

lib/Target/ARM/ARMInstrInfo.td

3925 ↗

(On Diff #129260)

The register class changes will also affect assembly, could you add tests for them?

test/MC/Disassembler/ARM/unpredictable-MVN-arm.txt

3 ↗

(On Diff #129260)

Could you add comments to these showing which instructions they are, and which fields are invalid?

[yroux]

Thanks for the review Oliver,

here is the new version of the patch.

Notice that the added assembly test doesn't cover all the cases of PC usage in MVN instruction because currently it doesn't report an error in these case:

	mvn	r5, pc, lsl r7
	mvn	r5, r6, lsl pc

Thus, I'm only testing here the register change impact on Rd, and I'm trying to fix MC and will complete the test coverage in a second patch.
Does it sounds good ?

[olista01]

LGTM, thanks!

llvm/trunk/lib/Target/ARM/ARMInstrInfo.td

def  MVNr  : AsI1<0b1111, (outs GPR:$Rd), (ins GPR:$Rm), DPFrm, IIC_iMVNr,
                   [(set GPR:$Rd, (not GPR:$Rm))]>, UnaryDP, Sched<[WriteALU]> {
   bits<4> Rd;
   bits<4> Rm;
   let Inst{25} = 0;
   let Inst{19-16} = 0b0000;
   let Inst{11-4} = 0b00000000;
   let Inst{15-12} = Rd;
   let Inst{3-0} = Rm;
+
+  let Unpredictable{19-16} = 0b1111;
 }
 def  MVNsi  : AsI1<0b1111, (outs GPR:$Rd), (ins so_reg_imm:$shift),
                   DPSoRegImmFrm, IIC_iMVNsr, "mvn", "\t$Rd, $shift",
                   [(set GPR:$Rd, (not so_reg_imm:$shift))]>, UnaryDP,
                   Sched<[WriteALU]> {
   bits<4> Rd;
   bits<12> shift;
   let Inst{25} = 0;
   let Inst{19-16} = 0b0000;
   let Inst{15-12} = Rd;
   let Inst{11-5} = shift{11-5};
   let Inst{4} = 0;
   let Inst{3-0} = shift{3-0};
+
+  let Unpredictable{19-16} = 0b1111;
 }
-def  MVNsr  : AsI1<0b1111, (outs GPR:$Rd), (ins so_reg_reg:$shift),
+def  MVNsr  : AsI1<0b1111, (outs GPRnopc:$Rd), (ins so_reg_reg:$shift),
                   DPSoRegRegFrm, IIC_iMVNsr, "mvn", "\t$Rd, $shift",
-                  [(set GPR:$Rd, (not so_reg_reg:$shift))]>, UnaryDP,
+                  [(set GPRnopc:$Rd, (not so_reg_reg:$shift))]>, UnaryDP,
                   Sched<[WriteALU]> {
   bits<4> Rd;
   bits<12> shift;
   let Inst{25} = 0;
   let Inst{19-16} = 0b0000;
   let Inst{15-12} = Rd;
   let Inst{11-8} = shift{11-8};
   let Inst{7} = 0;
   let Inst{6-5} = shift{6-5};
   let Inst{4} = 1;
   let Inst{3-0} = shift{3-0};
+
+  let Unpredictable{19-16} = 0b1111;
 }
 let isReMaterializable = 1, isAsCheapAsAMove = 1, isMoveImm = 1 in
 def  MVNi  : AsI1<0b1111, (outs GPR:$Rd), (ins mod_imm:$imm), DPFrm,
                   IIC_iMVNi, "mvn", "\t$Rd, $imm",
                   [(set GPR:$Rd, mod_imm_not:$imm)]>,UnaryDP, Sched<[WriteALU]> {
   bits<4> Rd;
   bits<12> imm;
   let Inst{25} = 1;

llvm/trunk/test/MC/ARM/diagnostics.s

 @ CHECK-ERRORS: error: immediate operand must a number in the range [0, 255]
 @ CHECK-ERRORS: error: immediate operand must an even number in the range [0, 30]
 
         @ Generic error for too few operands
         adds
         adds r0
 @ CHECK-ERRORS: error: too few operands for instruction
 @ CHECK-ERRORS: error: too few operands for instruction
+
+        @ Using pc for MVN
+  mvn pc, r6, lsl r7
+@ CHECK-ERRORS: error: invalid instruction, any one of the following would fix this:
+@ CHECK-ERRORS: note: operand must be a register in range [r0, r14]
+@ CHECK-ERRORS:         mvn pc, r6, lsl r7
+@ CHECK-ERRORS:             ^

llvm/trunk/test/MC/Disassembler/ARM/unpredictable-MVN-arm.txt

+# RUN: llvm-mc --disassemble %s -triple=armv7-linux-gnueabi 2>&1 | FileCheck %s
+
+# A8.8.116 MVN (register)
+# MVN(S)<c> <Rd>, <Rm>{, <shift>}
+#
+#  31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
+# -------------------------------------------------------------------------------------------------
+# | cond      | 0  0| 0| 1  1  1  1| S|(0)(0)(0)(0)| Rd       |  imm5        |type | 0| Rm        |
+# -------------------------------------------------------------------------------------------------
+
+# MVN  r2, r3  ; with bit 16 == 1 => Unpredictable
+# CHECK: potentially undefined
+# CHECK: 0x03 0x20 0xe1 0xe1
+0x03 0x20 0xe1 0xe1
+
+# A8.8.117 MVN (register-shifted register)
+# MVN(S)<c> <Rd>, <Rm>, <type> <Rs>
+#
+#  31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0
+# -------------------------------------------------------------------------------------------------
+# | cond      | 0  0| 0| 1  1  1  1| S|(0)(0)(0)(0)| Rd       | Rs        | 0|type | 1| Rm        |
+# -------------------------------------------------------------------------------------------------
+# if d == 15 || n == 15 || m == 15 then UNPREDICTABLE;
+
+# MVN  r5, pc, lsl r7
+# CHECK: potentially undefined
+# CHECK: 0x1f 0x57 0xe0 0xe1
+0x1f 0x57 0xe0 0xe1
+
+# MVN  pc, r6, lsl r7
+# CHECK: potentially undefined
+# CHECK: 0x16 0xf7 0xe0 0xe1
+0x16 0xf7 0xe0 0xe1
+
+# MVN  r5, r6, lsl pc
+# CHECK: potentially undefined
+# CHECK: 0x16 0x5f 0xe0 0xe1
+0x16 0x5f 0xe0 0xe1