[llvm] [GlobalIsel] Combine freeze (PR #93239)

[Thorsten Schütt via llvm-commits]

================
@@ -0,0 +1,607 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -o - -mtriple=aarch64-unknown-unknown -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s | FileCheck %s
+
+...
+---
+name:            freeze_register
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_register
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+    ; CHECK-NEXT: [[FREEZE:%[0-9]+]]:_(s64) = G_FREEZE [[COPY]]
+    ; CHECK-NEXT: $x0 = COPY [[FREEZE]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(s64) = COPY $x0
+    %1:_(s64) = G_FREEZE %0
+    $x0 = COPY %1(s64)
+    RET_ReallyLR implicit $x0
+
+...
+---
+name:            freeze_constant
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_constant
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 9
+    ; CHECK-NEXT: $x0 = COPY [[C]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %1:_(s64) = G_CONSTANT i64 9
+    %2:_(s64) = G_FREEZE %1
+    $x0 = COPY %2(s64)
+    RET_ReallyLR implicit $x0
+
+...
+---
+name:            freeze_fconstant
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_fconstant
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s64) = G_FCONSTANT double 9.000000e+00
+    ; CHECK-NEXT: $x0 = COPY [[C]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %1:_(s64) = G_FCONSTANT double 9.0
+    %2:_(s64) = G_FREEZE %1
+    $x0 = COPY %2(s64)
+    RET_ReallyLR implicit $x0
+...
+---
+name:            freeze_undef
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_undef
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[DEF:%[0-9]+]]:_(s64) = G_IMPLICIT_DEF
+    ; CHECK-NEXT: [[FREEZE:%[0-9]+]]:_(s64) = G_FREEZE [[DEF]]
+    ; CHECK-NEXT: $x0 = COPY [[FREEZE]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %1:_(s64) = G_IMPLICIT_DEF
+    %2:_(s64) = G_FREEZE %1
+    $x0 = COPY %2(s64)
+    RET_ReallyLR implicit $x0
+...
+---
+name:            freeze_freeze
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_freeze
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+    ; CHECK-NEXT: [[FREEZE:%[0-9]+]]:_(s64) = G_FREEZE [[COPY]]
+    ; CHECK-NEXT: $x0 = COPY [[FREEZE]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(s64) = COPY $x0
+    %1:_(s64) = G_FREEZE %0
+    %2:_(s64) = G_FREEZE %1
+    $x0 = COPY %2(s64)
+    RET_ReallyLR implicit $x0
+...
+---
+name:            freeze_buildvector
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_buildvector
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
+    ; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR [[COPY]](s32), [[COPY]](s32), [[COPY]](s32), [[COPY]](s32)
+    ; CHECK-NEXT: [[FREEZE:%[0-9]+]]:_(<4 x s32>) = G_FREEZE [[BUILD_VECTOR]]
+    ; CHECK-NEXT: $q0 = COPY [[FREEZE]](<4 x s32>)
+    ; CHECK-NEXT: RET_ReallyLR implicit $q0
+    %0:_(s32) = COPY $w0
+    %1:_(<4 x s32>) = G_BUILD_VECTOR %0(s32), %0(s32), %0(s32), %0(s32)
+    %2:_(<4 x s32>) = G_FREEZE %1
+    $q0 = COPY %2(<4 x s32>)
+    RET_ReallyLR implicit $q0
+...
+---
+name:            freeze_buildvector_const
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_buildvector_const
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %c:_(s32) = G_CONSTANT i32 6
+    ; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<4 x s32>) = G_BUILD_VECTOR %c(s32), %c(s32), %c(s32), %c(s32)
+    ; CHECK-NEXT: $q0 = COPY [[BUILD_VECTOR]](<4 x s32>)
+    ; CHECK-NEXT: RET_ReallyLR implicit $q0
+    %0:_(s32) = COPY $w0
+    %c:_(s32) = G_CONSTANT i32 6
+    %1:_(<4 x s32>) = G_BUILD_VECTOR %c(s32), %c(s32), %c(s32), %c(s32)
+    %2:_(<4 x s32>) = G_FREEZE %1
+    $q0 = COPY %2(<4 x s32>)
+    RET_ReallyLR implicit $q0
+...
+---
+name:            freeze_disjoint_or_fold_barrier
+body:             |
+  bb.1:
+    liveins: $w0
+
+    ; CHECK-LABEL: name: freeze_disjoint_or_fold_barrier
+    ; CHECK: liveins: $w0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %cst:_(s64) = G_CONSTANT i64 9
+    ; CHECK-NEXT: %c:_(s64) = G_CONSTANT_FOLD_BARRIER %cst
+    ; CHECK-NEXT: $x0 = COPY %c(s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(s64) = COPY $x0
+    %cst:_(s64) = G_CONSTANT i64 9
+    %c:_(s64) = G_CONSTANT_FOLD_BARRIER %cst
+    %1:_(s64) = disjoint G_OR %c, %c
----------------
tschuett wrote:

This combine is buggy. It ignores the `disjoint` flag and the G_OR disappears.

https://github.com/llvm/llvm-project/pull/93239