[llvm] Reapply "[LICM] Fold associative binary ops to promote code hoisting (#81608)" (PR #100377)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 25 05:59:05 PDT 2024
================
@@ -0,0 +1,229 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes=licm < %s | FileCheck %s
+
+; Fold ADD and remove old op if unused.
+; https://alive2.llvm.org/ce/z/wAY-Nd
+define void @add_one_use(i64 %c) {
+; CHECK-LABEL: @add_one_use(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = add i64 [[C:%.*]], [[C]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = add i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = add i64 %index, %c
+ %index.next = add i64 %step.add, %c
+ br label %loop
+}
+
+; Fold ADD and copy NUW if both ops have it.
+; https://alive2.llvm.org/ce/z/wAY-Nd
+define void @add_nuw(i64 %c) {
+; CHECK-LABEL: @add_nuw(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = add nuw i64 [[C:%.*]], [[C]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = add nuw i64 [[INDEX]], [[C]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = add nuw i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = add nuw i64 %index, %c
+ call void @use(i64 %step.add)
+ %index.next = add nuw i64 %step.add, %c
+ br label %loop
+}
+
+; Fold ADD but don't copy NUW if only one op has it.
+; https://alive2.llvm.org/ce/z/6n95Gf
+define void @add_no_nuw(i64 %c) {
+; CHECK-LABEL: @add_no_nuw(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = add i64 [[C:%.*]], [[C]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = add i64 [[INDEX]], [[C]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = add i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = add i64 %index, %c
+ call void @use(i64 %step.add)
+ %index.next = add nuw i64 %step.add, %c
+ br label %loop
+}
+
+; Fold ADD but don't copy NSW if one op has it.
+; https://alive2.llvm.org/ce/z/iz3dfB
+define void @add_no_nsw(i64 %c) {
+; CHECK-LABEL: @add_no_nsw(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = add i64 [[C:%.*]], [[C]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = add i64 [[INDEX]], [[C]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = add i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = add i64 %index, %c
+ call void @use(i64 %step.add)
+ %index.next = add nsw i64 %step.add, %c
+ br label %loop
+}
+
+; Fold ADD but don't copy NSW even if both ops have it.
+; https://alive2.llvm.org/ce/z/F9f43_
+define void @add_no_nsw_2(i64 %c) {
+; CHECK-LABEL: @add_no_nsw_2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[INVARIANT_OP:%.*]] = add i64 [[C:%.*]], [[C]]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT_REASS:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = add nsw i64 [[INDEX]], [[C]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT_REASS]] = add i64 [[INDEX]], [[INVARIANT_OP]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = add nsw i64 %index, %c
+ call void @use(i64 %step.add)
+ %index.next = add nsw i64 %step.add, %c
+ br label %loop
+}
+
+; Don't fold if the ops are different (even if they are both associative).
+define void @diff_ops(i64 %c) {
+; CHECK-LABEL: @diff_ops(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = add i64 [[INDEX]], [[C:%.*]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT]] = mul i64 [[STEP_ADD]], [[C]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = add i64 %index, %c
+ call void @use(i64 %step.add)
+ %index.next = mul i64 %step.add, %c
+ br label %loop
+}
+
+; Don't fold if the ops are not associative.
+define void @noassoc_ops(i64 %c) {
+; CHECK-LABEL: @noassoc_ops(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[STEP_ADD:%.*]] = sub i64 [[INDEX]], [[C:%.*]]
+; CHECK-NEXT: call void @use(i64 [[STEP_ADD]])
+; CHECK-NEXT: [[INDEX_NEXT]] = sub i64 [[STEP_ADD]], [[C]]
+; CHECK-NEXT: br label [[LOOP]]
+;
+entry:
+ br label %loop
+
+loop:
+ %index = phi i64 [ 0, %entry ], [ %index.next, %loop ]
+ %step.add = sub i64 %index, %c
+ call void @use(i64 %step.add)
+ %index.next = sub i64 %step.add, %c
+ br label %loop
+}
+
+; Don't fold floating-point ops, even if they are associative.
----------------
nikic wrote:
Maybe clarify here that the transform is valid, we just don't do it yet.
https://github.com/llvm/llvm-project/pull/100377
More information about the llvm-commits
mailing list