[llvm] [AMDGPU] GCNRegPressure printing pass for testing. (PR #70031)

[Valery Pykhtin via llvm-commits]

================
@@ -0,0 +1,388 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 3
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 --filetype=null --run-pass=amdgpu-print-rp %s 2>&1 >/dev/null | FileCheck %s --check-prefix=RP --check-prefix=RPU
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 --filetype=null --run-pass=amdgpu-print-rp -amdgpu-print-rp-downward %s 2>&1 >/dev/null | FileCheck %s --check-prefix=RP --check-prefix=RPD
+
+
+---
+name:  trivial
+tracksRegLiveness: true
+body:             |
+  ; RP-LABEL: name: trivial
+  ; RP: bb.0:
+  ; RP-NEXT:   Live-in:
+  ; RP-NEXT:   SGPR  VGPR
+  ; RP-NEXT:   0     0
+  ; RP-NEXT:   0     1      %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+  ; RP-NEXT:   0     1
+  ; RP-NEXT:   2     1      %1:sgpr_64 = IMPLICIT_DEF
+  ; RP-NEXT:   2     1
+  ; RP-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000F
+  ; RP-NEXT:   Live-thr:
+  ; RP-NEXT: bb.1:
+  ; RP-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000F
+  ; RP-NEXT:   SGPR  VGPR
+  ; RP-NEXT:   2     1
+  ; RP-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000F
+  ; RP-NEXT:   Live-thr: %0:0000000000000003 %1:000000000000000F
+  ; RP-NEXT: bb.2:
+  ; RP-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000F
+  ; RP-NEXT:   SGPR  VGPR
+  ; RP-NEXT:   2     1
+  ; RP-NEXT:   2     1      S_NOP 0, implicit %0:vgpr_32, implicit %1:sgpr_64
+  ; RP-NEXT:   0     0
+  ; RP-NEXT:   Live-out:
+  ; RP-NEXT:   Live-thr:
+  bb.0:
+    %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+    %1:sgpr_64 = IMPLICIT_DEF
+  bb.1:
+
+  bb.2:
+    S_NOP 0, implicit %0, implicit %1
+...
+
+# This testcase shows the problem with LiveIntervals: it doesn't create
+# subranges for undefined but used subregisters. Upward tracker is able to see
+# the use of undefined subregister and tracks it correctly.
----------------
vpykhtin wrote:

Right, given that both trackers are already optimistic in that they believe the allocator can reuse for example, unused subregs of %0.sub0:sgpr_128 use, so this is the same situation here.

https://github.com/llvm/llvm-project/pull/70031