[llvm] [AtomicExpandPass] Add umin, smin, umax, smax to isIdempotentRMW (PR #142277)
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Sat May 31 08:36:42 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: AZero13 (AZero13)
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/142277.diff
3 Files Affected:
- (modified) llvm/lib/CodeGen/AtomicExpandPass.cpp (+7-1)
- (modified) llvm/test/CodeGen/X86/atomic-idempotent.ll (+222)
- (modified) llvm/test/Transforms/InstCombine/atomicrmw.ll (+20)
``````````diff
diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index c376de877ac7d..2b86bed152d7c 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -1580,10 +1580,16 @@ bool AtomicExpandImpl::isIdempotentRMW(AtomicRMWInst *RMWI) {
case AtomicRMWInst::Sub:
case AtomicRMWInst::Or:
case AtomicRMWInst::Xor:
+ case AtomicRMWInst::UMax: // umax(x, 0) == x
return C->isZero();
case AtomicRMWInst::And:
return C->isMinusOne();
- // FIXME: we could also treat Min/Max/UMin/UMax by the INT_MIN/INT_MAX/...
+ case AtomicRMWInst::Max: // max(x, INT_MIN) == x
+ return C->isMinValue(/*isSigned=*/true);
+ case AtomicRMWInst::Min: // min(x, INT_MAX) == x
+ return C->isMaxValue(/*isSigned=*/true);
+ case AtomicRMWInst::UMin: // umin(x, UINT_MAX) == x
+ return C->isMaxValue(/*isSigned=*/false);
default:
return false;
}
diff --git a/llvm/test/CodeGen/X86/atomic-idempotent.ll b/llvm/test/CodeGen/X86/atomic-idempotent.ll
index 020f9eb793102..db3dedb6f7ac0 100644
--- a/llvm/test/CodeGen/X86/atomic-idempotent.ll
+++ b/llvm/test/CodeGen/X86/atomic-idempotent.ll
@@ -622,4 +622,226 @@ define void @or8_nouse_seq_cst(ptr %p) #0 {
ret void
}
+define void @atomic_umin_uint_max(ptr %addr) {
+; CHECK-LABEL: @atomic_umin_uint_max(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i32 0 monotonic, align 4
+; CHECK-NEXT: ret i32 [[RES]]
+;
+; X64-LABEL: atomic_umin_uint_max:
+; X64: # %bb.0:
+; X64-NEXT: lock orl $0, -{{[0-9]+}}(%rsp)
+; X64-NEXT: movl (%rdi), %eax
+; X64-NEXT: retq
+;
+; X86-SSE2-LABEL: atomic_umin_uint_max:
+; X86-SSE2: # %bb.0:
+; X86-SSE2-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SSE2-NEXT: mfence
+; X86-SSE2-NEXT: movl (%eax), %eax
+; X86-SSE2-NEXT: retl
+;
+; X86-SLM-LABEL: atomic_umin_uint_max:
+; X86-SLM: # %bb.0:
+; X86-SLM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SLM-NEXT: lock orl $0, (%esp)
+; X86-SLM-NEXT: movl (%eax), %eax
+; X86-SLM-NEXT: retl
+;
+; X86-ATOM-LABEL: atomic_umin_uint_max:
+; X86-ATOM: # %bb.0:
+; X86-ATOM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-ATOM-NEXT: lock orl $0, (%esp)
+; X86-ATOM-NEXT: movl (%eax), %eax
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: retl
+ atomicrmw umin ptr %addr, i32 -1 seq_cst
+ ret void
+}
+
+define void @atomic_umax_zero(ptr %addr) {
+; CHECK-LABEL: @atomic_umax_zero(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i32 0 monotonic, align 4
+; CHECK-NEXT: ret i32 [[RES]]
+;
+; X64-LABEL: atomic_umax_zero:
+; X64: # %bb.0:
+; X64-NEXT: lock orl $0, -{{[0-9]+}}(%rsp)
+; X64-NEXT: movl (%rdi), %eax
+; X64-NEXT: retq
+;
+; X86-SSE2-LABEL: atomic_umax_zero:
+; X86-SSE2: # %bb.0:
+; X86-SSE2-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SSE2-NEXT: mfence
+; X86-SSE2-NEXT: movl (%eax), %eax
+; X86-SSE2-NEXT: retl
+;
+; X86-SLM-LABEL: atomic_umax_zero:
+; X86-SLM: # %bb.0:
+; X86-SLM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SLM-NEXT: lock orl $0, (%esp)
+; X86-SLM-NEXT: movl (%eax), %eax
+; X86-SLM-NEXT: retl
+;
+; X86-ATOM-LABEL: atomic_umax_zero:
+; X86-ATOM: # %bb.0:
+; X86-ATOM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-ATOM-NEXT: lock orl $0, (%esp)
+; X86-ATOM-NEXT: movl (%eax), %eax
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: retl
+ atomicrmw umax ptr %addr, i32 0 seq_cst
+ ret void
+}
+
+define void @atomic_min_smax_char(ptr %addr) {
+; CHECK-LABEL: @atomic_min_smax_char(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i8 0 monotonic, align 1
+; CHECK-NEXT: ret i8 [[RES]]
+;
+; X64-LABEL: atomic_min_smax_char:
+; X64: # %bb.0:
+; X64-NEXT: lock orl $0, -{{[0-9]+}}(%rsp)
+; X64-NEXT: movzbl (%rdi), %eax
+; X64-NEXT: retq
+;
+; X86-SSE2-LABEL: atomic_min_smax_char:
+; X86-SSE2: # %bb.0:
+; X86-SSE2-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SSE2-NEXT: mfence
+; X86-SSE2-NEXT: movzbl (%eax), %eax
+; X86-SSE2-NEXT: retl
+;
+; X86-SLM-LABEL: atomic_min_smax_char:
+; X86-SLM: # %bb.0:
+; X86-SLM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SLM-NEXT: lock orl $0, (%esp)
+; X86-SLM-NEXT: movzbl (%eax), %eax
+; X86-SLM-NEXT: retl
+;
+; X86-ATOM-LABEL: atomic_min_smax_char:
+; X86-ATOM: # %bb.0:
+; X86-ATOM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-ATOM-NEXT: lock orl $0, (%esp)
+; X86-ATOM-NEXT: movzbl (%eax), %eax
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: retl
+ atomicrmw min ptr %addr, i8 127 seq_cst
+ ret void
+}
+
+define void @atomic_max_smin_char(ptr %addr) {
+; CHECK-LABEL: @atomic_max_smin_char(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i8 0 monotonic, align 1
+; CHECK-NEXT: ret i8 [[RES]]
+;
+; X64-LABEL: atomic_max_smin_char:
+; X64: # %bb.0:
+; X64-NEXT: lock orl $0, -{{[0-9]+}}(%rsp)
+; X64-NEXT: movzbl (%rdi), %eax
+; X64-NEXT: retq
+;
+; X86-SSE2-LABEL: atomic_max_smin_char:
+; X86-SSE2: # %bb.0:
+; X86-SSE2-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SSE2-NEXT: mfence
+; X86-SSE2-NEXT: movzbl (%eax), %eax
+; X86-SSE2-NEXT: retl
+;
+; X86-SLM-LABEL: atomic_max_smin_char:
+; X86-SLM: # %bb.0:
+; X86-SLM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SLM-NEXT: lock orl $0, (%esp)
+; X86-SLM-NEXT: movzbl (%eax), %eax
+; X86-SLM-NEXT: retl
+;
+; X86-ATOM-LABEL: atomic_max_smin_char:
+; X86-ATOM: # %bb.0:
+; X86-ATOM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-ATOM-NEXT: lock orl $0, (%esp)
+; X86-ATOM-NEXT: movzbl (%eax), %eax
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: retl
+ atomicrmw max ptr %addr, i8 -128 seq_cst
+ ret void
+}
+
+define void @atomic_min_umax_char(ptr %addr) {
+; CHECK-LABEL: @atomic_min_umax_char(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i8 0 monotonic, align 1
+; CHECK-NEXT: ret i8 [[RES]]
+;
+; X64-LABEL: atomic_min_umax_char:
+; X64: # %bb.0:
+; X64-NEXT: lock orl $0, -{{[0-9]+}}(%rsp)
+; X64-NEXT: movzbl (%rdi), %eax
+; X64-NEXT: retq
+;
+; X86-SSE2-LABEL: atomic_min_umax_char:
+; X86-SSE2: # %bb.0:
+; X86-SSE2-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SSE2-NEXT: mfence
+; X86-SSE2-NEXT: movzbl (%eax), %eax
+; X86-SSE2-NEXT: retl
+;
+; X86-SLM-LABEL: atomic_min_umax_char:
+; X86-SLM: # %bb.0:
+; X86-SLM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SLM-NEXT: lock orl $0, (%esp)
+; X86-SLM-NEXT: movzbl (%eax), %eax
+; X86-SLM-NEXT: retl
+;
+; X86-ATOM-LABEL: atomic_min_umax_char:
+; X86-ATOM: # %bb.0:
+; X86-ATOM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-ATOM-NEXT: lock orl $0, (%esp)
+; X86-ATOM-NEXT: movzbl (%eax), %eax
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: retl
+ atomicrmw umin ptr %addr, i8 255 seq_cst
+ ret void
+}
+
+define void @atomic_max_umin_char(ptr %addr) {
+; CHECK-LABEL: @atomic_max_umin_char(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i8 0 monotonic, align 1
+; CHECK-NEXT: ret i8 [[RES]]
+;
+; X64-LABEL: atomic_max_umin_char:
+; X64: # %bb.0:
+; X64-NEXT: lock orl $0, -{{[0-9]+}}(%rsp)
+; X64-NEXT: movzbl (%rdi), %eax
+; X64-NEXT: retq
+;
+; X86-SSE2-LABEL: atomic_max_umin_char:
+; X86-SSE2: # %bb.0:
+; X86-SSE2-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SSE2-NEXT: mfence
+; X86-SSE2-NEXT: movzbl (%eax), %eax
+; X86-SSE2-NEXT: retl
+;
+; X86-SLM-LABEL: atomic_max_umin_char:
+; X86-SLM: # %bb.0:
+; X86-SLM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-SLM-NEXT: lock orl $0, (%esp)
+; X86-SLM-NEXT: movzbl (%eax), %eax
+; X86-SLM-NEXT: retl
+;
+; X86-ATOM-LABEL: atomic_max_umin_char:
+; X86-ATOM: # %bb.0:
+; X86-ATOM-NEXT: movl {{[0-9]+}}(%esp), %eax
+; X86-ATOM-NEXT: lock orl $0, (%esp)
+; X86-ATOM-NEXT: movzbl (%eax), %eax
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: nop
+; X86-ATOM-NEXT: retl
+ atomicrmw umax ptr %addr, i8 0 seq_cst
+ ret void
+}
+
attributes #0 = { nounwind }
diff --git a/llvm/test/Transforms/InstCombine/atomicrmw.ll b/llvm/test/Transforms/InstCombine/atomicrmw.ll
index ca5ffd110ad61..b6c0e1e810f96 100644
--- a/llvm/test/Transforms/InstCombine/atomicrmw.ll
+++ b/llvm/test/Transforms/InstCombine/atomicrmw.ll
@@ -85,6 +85,26 @@ define i8 @atomic_max_smin_char(ptr %addr) {
ret i8 %res
}
+; Idempotent atomicrmw are still canonicalized.
+define i8 @atomic_min_umax_char(ptr %addr) {
+; CHECK-LABEL: @atomic_min_umax_char(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i8 0 monotonic, align 1
+; CHECK-NEXT: ret i8 [[RES]]
+;
+ %res = atomicrmw umin ptr %addr, i8 255 monotonic
+ ret i8 %res
+}
+
+; Idempotent atomicrmw are still canonicalized.
+define i8 @atomic_max_umin_char(ptr %addr) {
+; CHECK-LABEL: @atomic_max_umin_char(
+; CHECK-NEXT: [[RES:%.*]] = atomicrmw or ptr [[ADDR:%.*]], i8 0 monotonic, align 1
+; CHECK-NEXT: ret i8 [[RES]]
+;
+ %res = atomicrmw umax ptr %addr, i8 0 monotonic
+ ret i8 %res
+}
+
; Idempotent atomicrmw are still canonicalized.
define float @atomic_fsub_zero(ptr %addr) {
; CHECK-LABEL: @atomic_fsub_zero(
``````````
</details>
https://github.com/llvm/llvm-project/pull/142277
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