[llvm] [AMDGPU][MC][True16] Support VOP2 instructions with true16 format (PR #115233)

[Joe Nash via llvm-commits]

================
@@ -446,49 +446,78 @@
 # GFX12: v_cvt_pk_rtz_f16_f32_e32 v255, 0xaf123456, v255 ; encoding: [0xff,0xfe,0xff,0x5f,0x56,0x34,0x12,0xaf]
 
 0x01,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, v1, v2, 0xfe0b          ; encoding: [0x01,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, v1.l, v2.l, 0xfe0b    ; encoding: [0x01,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, v1, v2, 0xfe0b          ; encoding: [0x01,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x7f,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, v127, v2, 0xfe0b        ; encoding: [0x7f,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, v127.l, v2.l, 0xfe0b  ; encoding: [0x7f,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, v127, v2, 0xfe0b        ; encoding: [0x7f,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x01,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, s1, v2, 0xfe0b          ; encoding: [0x01,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, s1, v2.l, 0xfe0b      ; encoding: [0x01,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, s1, v2, 0xfe0b          ; encoding: [0x01,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x69,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, s105, v2, 0xfe0b        ; encoding: [0x69,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, s105, v2.l, 0xfe0b    ; encoding: [0x69,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, s105, v2, 0xfe0b        ; encoding: [0x69,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x6a,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, vcc_lo, v2, 0xfe0b      ; encoding: [0x6a,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, vcc_lo, v2.l, 0xfe0b  ; encoding: [0x6a,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, vcc_lo, v2, 0xfe0b      ; encoding: [0x6a,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x6b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, vcc_hi, v2, 0xfe0b      ; encoding: [0x6b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, vcc_hi, v2.l, 0xfe0b  ; encoding: [0x6b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, vcc_hi, v2, 0xfe0b      ; encoding: [0x6b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x7b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, ttmp15, v2, 0xfe0b      ; encoding: [0x7b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, ttmp15, v2.l, 0xfe0b  ; encoding: [0x7b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, ttmp15, v2, 0xfe0b      ; encoding: [0x7b,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x7d,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, m0, v2, 0xfe0b          ; encoding: [0x7d,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, m0, v2.l, 0xfe0b      ; encoding: [0x7d,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, m0, v2, 0xfe0b          ; encoding: [0x7d,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x7e,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, exec_lo, v2, 0xfe0b     ; encoding: [0x7e,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, exec_lo, v2.l, 0xfe0b ; encoding: [0x7e,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, exec_lo, v2, 0xfe0b     ; encoding: [0x7e,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x7f,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, exec_hi, v2, 0xfe0b     ; encoding: [0x7f,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, exec_hi, v2.l, 0xfe0b ; encoding: [0x7f,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, exec_hi, v2, 0xfe0b     ; encoding: [0x7f,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0x7c,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, null, v2, 0xfe0b        ; encoding: [0x7c,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, null, v2.l, 0xfe0b    ; encoding: [0x7c,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, null, v2, 0xfe0b        ; encoding: [0x7c,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0xc1,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, -1, v2, 0xfe0b          ; encoding: [0xc1,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, -1, v2.l, 0xfe0b      ; encoding: [0xc1,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, -1, v2, 0xfe0b          ; encoding: [0xc1,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0xf0,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, 0.5, v2, 0xfe0b         ; encoding: [0xf0,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, 0.5, v2.l, 0xfe0b     ; encoding: [0xf0,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, 0.5, v2, 0xfe0b         ; encoding: [0xf0,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0xfd,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v5, src_scc, v2, 0xfe0b     ; encoding: [0xfd,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v5.l, src_scc, v2.l, 0xfe0b ; encoding: [0xfd,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, src_scc, v2, 0xfe0b     ; encoding: [0xfd,0x04,0x0a,0x70,0x0b,0xfe,0x00,0x00]
 
 0xff,0xfe,0xfe,0x70,0x0b,0xfe,0x00,0x00
-# GFX12: v_fmaak_f16 v127, 0xfe0b, v127, 0xfe0b  ; encoding: [0xff,0xfe,0xfe,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-REAL16: v_fmaak_f16 v127.l, 0xfe0b, v127.l, 0xfe0b ; encoding: [0xff,0xfe,0xfe,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v127, 0xfe0b, v127, 0xfe0b  ; encoding: [0xff,0xfe,0xfe,0x70,0x0b,0xfe,0x00,0x00]
+
+0x81,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00
+# GFX12-REAL16: v_fmaak_f16 v5.l, v1.h, v2.l, 0xfe0b    ; encoding: [0x81,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
+# GFX12-FAKE16: v_fmaak_f16 v5, v129/*Invalid register, operand has 'VS_32_Lo128' register class*/, v2, 0xfe0b ; encoding: [0x81,0x05,0x0a,0x70,0x0b,0xfe,0x00,0x00]
----------------
Sisyph wrote:

I think the output is confusing and not useful. For example the following. The disassembler did not work on the full 8 bytes and spit out the last 4 bytes disassembled. 

```
0xfa,0x04,0x0b,0x6d,0x81,0x60,0x01,0x13
# GFX12-REAL16: v_fmac_f16_dpp v5.h, v1.h, v2.h row_xmask:0 row_mask:0x1 bank_mask:0x3 ; encoding: [0xfa,0x04,0x0b,0x6d,0x81,0x60,0x01,0x13]
# GFX12-FAKE16: v_mul_i32_i24_e32 v128, 1, v176         ; encoding: [0x81,0x60,0x01,0x13]
```
Crashing is perhaps the only behavior worth testing, and that could be done with --not-crash in the runline.

https://github.com/llvm/llvm-project/pull/115233