[llvm] [AMDGPU] Don't allow nesting hard clauses. (PR #188460)
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Wed Mar 25 04:21:59 PDT 2026
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-amdgpu
Author: sstipano
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/188460.diff
2 Files Affected:
- (modified) llvm/lib/Target/AMDGPU/SIInsertHardClauses.cpp (+14-1)
- (added) llvm/test/CodeGen/AMDGPU/si-insert-hard-clauses-no-nesting.mir (+150)
``````````diff
diff --git a/llvm/lib/Target/AMDGPU/SIInsertHardClauses.cpp b/llvm/lib/Target/AMDGPU/SIInsertHardClauses.cpp
index 0a68512668c7d..af2020d4304e9 100644
--- a/llvm/lib/Target/AMDGPU/SIInsertHardClauses.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInsertHardClauses.cpp
@@ -209,8 +209,21 @@ class SIInsertHardClauses {
bool Changed = false;
for (auto &MBB : MF) {
ClauseInfo CI;
+ unsigned ExistingClauseRemaining = 0;
for (auto &MI : MBB) {
- HardClauseType Type = getHardClauseType(MI);
+ HardClauseType Type;
+ if (ExistingClauseRemaining) {
+ if (!MI.isMetaInstruction())
+ ExistingClauseRemaining--;
+ Type = HARDCLAUSE_ILLEGAL;
+ } else if (MI.getOpcode() == AMDGPU::S_CLAUSE) {
+ // Respect existing explicit clauses. Re-clausing instructions that
+ // are already covered by an S_CLAUSE can create nested clauses.
+ ExistingClauseRemaining = (MI.getOperand(0).getImm() & 63) + 1;
+ Type = HARDCLAUSE_ILLEGAL;
+ } else {
+ Type = getHardClauseType(MI);
+ }
int64_t Dummy1;
bool Dummy2;
diff --git a/llvm/test/CodeGen/AMDGPU/si-insert-hard-clauses-no-nesting.mir b/llvm/test/CodeGen/AMDGPU/si-insert-hard-clauses-no-nesting.mir
new file mode 100644
index 0000000000000..e4e314b23dc76
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/si-insert-hard-clauses-no-nesting.mir
@@ -0,0 +1,150 @@
+# RUN: llc -mtriple=amdgcn -mcpu=gfx1100 -verify-machineinstrs -run-pass si-insert-hard-clauses %s -o - | FileCheck %s
+# RUN: llc -mtriple=amdgcn -mcpu=gfx1200 -verify-machineinstrs -run-pass si-insert-hard-clauses %s -o - | FileCheck %s
+
+---
+name: no_nested_clause_from_existing_clause
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $sgpr0_sgpr1
+ ; CHECK-LABEL: name: no_nested_clause_from_existing_clause
+ ; CHECK: liveins: $sgpr0_sgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit $sgpr0_sgpr1 {
+ ; CHECK-NEXT: S_CLAUSE 1
+ ; CHECK-NEXT: $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ ; CHECK-NEXT: KILL undef renamable $sgpr0
+ ; CHECK-NEXT: $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ ; CHECK-NEXT: }
+ ; CHECK-NOT: S_CLAUSE
+ ; CHECK: S_ENDPGM 0
+ BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit $sgpr0_sgpr1 {
+ S_CLAUSE 1
+ $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ KILL undef renamable $sgpr0
+ $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ }
+ S_ENDPGM 0
+...
+
+---
+name: no_nested_clause_longer_existing_clause
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $sgpr0_sgpr1
+ ; CHECK-LABEL: name: no_nested_clause_longer_existing_clause
+ ; CHECK: liveins: $sgpr0_sgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit-def $sgpr4, implicit $sgpr0_sgpr1 {
+ ; CHECK-NEXT: S_CLAUSE 2
+ ; CHECK-NEXT: $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ ; CHECK-NEXT: KILL undef renamable $sgpr0
+ ; CHECK-NEXT: $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ ; CHECK-NEXT: KILL undef renamable $sgpr0
+ ; CHECK-NEXT: $sgpr4 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 8, 0
+ ; CHECK-NEXT: }
+ ; CHECK-NOT: S_CLAUSE
+ ; CHECK: S_ENDPGM 0
+ BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit-def $sgpr4, implicit $sgpr0_sgpr1 {
+ S_CLAUSE 2
+ $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ KILL undef renamable $sgpr0
+ $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ KILL undef renamable $sgpr0
+ $sgpr4 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 8, 0
+ }
+ S_ENDPGM 0
+...
+
+---
+name: no_nested_clause_existing_flat_clause
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $vgpr0_vgpr1
+ ; CHECK-LABEL: name: no_nested_clause_existing_flat_clause
+ ; CHECK: liveins: $vgpr0_vgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: BUNDLE implicit-def $vgpr2, implicit-def $vgpr3, implicit-def $vgpr4, implicit $vgpr0_vgpr1, implicit $exec, implicit $flat_scr {
+ ; CHECK-NEXT: S_CLAUSE 2
+ ; CHECK-NEXT: $vgpr2 = FLAT_LOAD_DWORD $vgpr0_vgpr1, 0, 0, implicit $exec, implicit $flat_scr
+ ; CHECK-NEXT: $vgpr3 = FLAT_LOAD_DWORD $vgpr0_vgpr1, 4, 0, implicit $exec, implicit $flat_scr
+ ; CHECK-NEXT: $vgpr4 = FLAT_LOAD_DWORD $vgpr0_vgpr1, 8, 0, implicit $exec, implicit $flat_scr
+ ; CHECK-NEXT: }
+ ; CHECK-NOT: S_CLAUSE
+ ; CHECK: S_ENDPGM 0
+ BUNDLE implicit-def $vgpr2, implicit-def $vgpr3, implicit-def $vgpr4, implicit $vgpr0_vgpr1, implicit $exec, implicit $flat_scr {
+ S_CLAUSE 2
+ $vgpr2 = FLAT_LOAD_DWORD $vgpr0_vgpr1, 0, 0, implicit $exec, implicit $flat_scr
+ $vgpr3 = FLAT_LOAD_DWORD $vgpr0_vgpr1, 4, 0, implicit $exec, implicit $flat_scr
+ $vgpr4 = FLAT_LOAD_DWORD $vgpr0_vgpr1, 8, 0, implicit $exec, implicit $flat_scr
+ }
+ S_ENDPGM 0
+...
+
+---
+name: no_nested_clause_but_new_clause_afterwards
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $sgpr0_sgpr1
+ ; CHECK-LABEL: name: no_nested_clause_but_new_clause_afterwards
+ ; CHECK: liveins: $sgpr0_sgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit $sgpr0_sgpr1 {
+ ; CHECK-NEXT: S_CLAUSE 1
+ ; CHECK-NEXT: $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ ; CHECK-NEXT: KILL undef renamable $sgpr0
+ ; CHECK-NEXT: $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ ; CHECK-NEXT: }
+ ; CHECK-NEXT: BUNDLE implicit-def $sgpr4, implicit-def $sgpr5, implicit $sgpr0_sgpr1 {
+ ; CHECK-NEXT: S_CLAUSE 1
+ ; CHECK-NEXT: $sgpr4 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 8, 0
+ ; CHECK-NEXT: $sgpr5 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 12, 0
+ ; CHECK-NEXT: }
+ ; CHECK: S_ENDPGM 0
+ BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit $sgpr0_sgpr1 {
+ S_CLAUSE 1
+ $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ KILL undef renamable $sgpr0
+ $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ }
+ $sgpr4 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 8, 0
+ $sgpr5 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 12, 0
+ S_ENDPGM 0
+...
+
+---
+name: new_clause_after_existing_clause_with_gap
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $sgpr0_sgpr1
+ ; CHECK-LABEL: name: new_clause_after_existing_clause_with_gap
+ ; CHECK: liveins: $sgpr0_sgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit $sgpr0_sgpr1 {
+ ; CHECK-NEXT: S_CLAUSE 1
+ ; CHECK-NEXT: $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ ; CHECK-NEXT: KILL undef renamable $sgpr0
+ ; CHECK-NEXT: $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ ; CHECK-NEXT: }
+ ; CHECK-NEXT: $sgpr6 = S_MOV_B32 0
+ ; CHECK-NEXT: BUNDLE implicit-def $sgpr4, implicit-def $sgpr5, implicit $sgpr0_sgpr1 {
+ ; CHECK-NEXT: S_CLAUSE 1
+ ; CHECK-NEXT: $sgpr4 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 8, 0
+ ; CHECK-NEXT: $sgpr5 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 12, 0
+ ; CHECK-NEXT: }
+ ; CHECK: S_ENDPGM 0
+ BUNDLE implicit-def $sgpr2, implicit-def $sgpr3, implicit $sgpr0_sgpr1 {
+ S_CLAUSE 1
+ $sgpr2 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 0, 0
+ KILL undef renamable $sgpr0
+ $sgpr3 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 4, 0
+ }
+ $sgpr6 = S_MOV_B32 0
+ $sgpr4 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 8, 0
+ $sgpr5 = S_LOAD_DWORD_IMM $sgpr0_sgpr1, 12, 0
+ S_ENDPGM 0
+...
``````````
</details>
https://github.com/llvm/llvm-project/pull/188460
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