aa485384d7
Despite the fact that it is legal, it is not profitable. It may prevent Loop Guard Widening to happen. Because of bug described at https://github.com/llvm/llvm-project/issues/60234, now the guard widening is only possible when condtion we want to add is available at the point of the widenable_condition() of dominating guard. It means that, if all such calls are hoisted out of loop, and the loop conditions depend on loop-variants, we cannot widen. Hoisting is otherwise not helpful, because it does not introduce any optimization opportunities. Differential Revision: https://reviews.llvm.org/D146274 Reviewed By: apilipenko
128 lines
5.1 KiB
LLVM
128 lines
5.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -S -aa-pipeline=basic-aa -passes='require<opt-remark-emit>,make-guards-explicit,loop-mssa(licm)' < %s | FileCheck %s
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declare void @llvm.experimental.guard(i1,...)
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declare void @maythrow()
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; Make sure that we do not hoist widenable_cond out of loop.
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; Widenable conditions don't actually alias anything or throw, however
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; hoisting them is not profitable because it can prevent guard widening
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; in loop.
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; If we want to widen guards in branch form, we need to generate them
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; at the point of widenable_condition call
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; (see https://github.com/llvm/llvm-project/issues/60234). Because of
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; this, hoisting a widenable condition out of loop can make widening of
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; in-loop conditions impossible (e.g. if they depend on loop variant). On
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; the other hand, hoisting of the WC doesn't really see profitable,
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; because it will be optimized away later anyways. So the test checks that
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; LICM will not move it out of loop.
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define void @do_not_hoist_widenable_cond(i1 %cond, i32 %N, i32 %M) {
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; CHECK-LABEL: @do_not_hoist_widenable_cond(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[GUARDED:%.*]] ]
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; CHECK-NEXT: [[GUARD_COND:%.*]] = icmp slt i32 [[IV]], [[N:%.*]]
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; CHECK-NEXT: [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
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; CHECK-NEXT: [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[GUARD_COND]], [[WIDENABLE_COND]]
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; CHECK-NEXT: br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED]], label [[DEOPT:%.*]], !prof [[PROF0:![0-9]+]]
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; CHECK: deopt:
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; CHECK-NEXT: call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
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; CHECK-NEXT: ret void
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; CHECK: guarded:
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp slt i32 [[IV]], [[M:%.*]]
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; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
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%guard_cond = icmp slt i32 %iv, %N
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call void(i1, ...) @llvm.experimental.guard(i1 %guard_cond) [ "deopt"() ]
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%loop_cond = icmp slt i32 %iv, %M
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%iv.next = add i32 %iv, 1
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br i1 %loop_cond, label %loop, label %exit
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exit:
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ret void
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}
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define void @do_not_hoist_widenable_cond_speculate(i1 %cond, i32 %N, i32 %M) {
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; CHECK-LABEL: @do_not_hoist_widenable_cond_speculate(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[GUARDED:%.*]] ]
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; CHECK-NEXT: [[GUARD_COND:%.*]] = icmp slt i32 [[IV]], [[N:%.*]]
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; CHECK-NEXT: call void @maythrow()
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; CHECK-NEXT: [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
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; CHECK-NEXT: [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[GUARD_COND]], [[WIDENABLE_COND]]
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; CHECK-NEXT: br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED]], label [[DEOPT:%.*]], !prof [[PROF0]]
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; CHECK: deopt:
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; CHECK-NEXT: call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
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; CHECK-NEXT: ret void
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; CHECK: guarded:
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp slt i32 [[IV]], [[M:%.*]]
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; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
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%guard_cond = icmp slt i32 %iv, %N
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call void @maythrow()
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call void(i1, ...) @llvm.experimental.guard(i1 %guard_cond) [ "deopt"() ]
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%loop_cond = icmp slt i32 %iv, %M
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%iv.next = add i32 %iv, 1
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br i1 %loop_cond, label %loop, label %exit
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exit:
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ret void
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}
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define void @hoist_invariant_load(i1 %cond, ptr %np, i32 %M) {
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; CHECK-LABEL: @hoist_invariant_load(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[N:%.*]] = load i32, ptr [[NP:%.*]], align 4
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[GUARDED:%.*]] ]
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; CHECK-NEXT: [[GUARD_COND:%.*]] = icmp slt i32 [[IV]], [[N]]
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; CHECK-NEXT: [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
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; CHECK-NEXT: [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[GUARD_COND]], [[WIDENABLE_COND]]
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; CHECK-NEXT: br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED]], label [[DEOPT:%.*]], !prof [[PROF0]]
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; CHECK: deopt:
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; CHECK-NEXT: call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
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; CHECK-NEXT: ret void
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; CHECK: guarded:
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp slt i32 [[IV]], [[M:%.*]]
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; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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;
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
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%N = load i32, ptr %np
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%guard_cond = icmp slt i32 %iv, %N
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call void(i1, ...) @llvm.experimental.guard(i1 %guard_cond) [ "deopt"() ]
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%loop_cond = icmp slt i32 %iv, %M
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%iv.next = add i32 %iv, 1
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br i1 %loop_cond, label %loop, label %exit
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exit:
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ret void
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}
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