e63f0f50fa
In the case of a partial unswitch, we take the invariant part of an expression consisting of either conjunctions or disjunctions, and hoist it out of the loop, conditioning a branch on it (==the invariant part). We can't correctly calculate the branch probability of this new branch, but can use the probability of the existing branch as a bound. That would preserve block frequencies better than allowing for the default, static (50-50) probability for that branch. Issue #147390
90 lines
2.4 KiB
LLVM
90 lines
2.4 KiB
LLVM
; RUN: split-file %s %t
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; RUN: cat %t/main.ll %t/probable-or.prof > %t/probable-or.ll
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; RUN: cat %t/main.ll %t/probable-and.prof > %t/probable-and.ll
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; RUN: opt -passes='loop(simple-loop-unswitch<nontrivial>)' -S %t/probable-or.ll -o -| FileCheck %t/probable-or.prof
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; RUN: opt -passes='loop(simple-loop-unswitch<nontrivial>)' -S %t/probable-and.ll -o -| FileCheck %t/probable-and.prof
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;--- main.ll
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declare i32 @a()
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declare i32 @b()
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define i32 @or(ptr %ptr, i1 %cond) !prof !0 {
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entry:
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br label %loop_begin
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loop_begin:
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%v1 = load i1, ptr %ptr
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%cond_or = or i1 %v1, %cond
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br i1 %cond_or, label %loop_a, label %loop_b, !prof !1
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loop_a:
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call i32 @a()
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br label %latch
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loop_b:
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call i32 @b()
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br label %latch
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latch:
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%v2 = load i1, ptr %ptr
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br i1 %v2, label %loop_begin, label %loop_exit, !prof !2
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loop_exit:
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ret i32 0
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}
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define i32 @and(ptr %ptr, i1 %cond) !prof !0 {
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entry:
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br label %loop_begin
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loop_begin:
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%v1 = load i1, ptr %ptr
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%cond_and = and i1 %v1, %cond
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br i1 %cond_and, label %loop_a, label %loop_b, !prof !1
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loop_a:
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call i32 @a()
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br label %latch
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loop_b:
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call i32 @b()
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br label %latch
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latch:
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%v2 = load i1, ptr %ptr
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br i1 %v2, label %loop_begin, label %loop_exit, !prof !2
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loop_exit:
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ret i32 0
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}
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;--- probable-or.prof
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!0 = !{!"function_entry_count", i32 10}
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!1 = !{!"branch_weights", i32 1, i32 1000}
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!2 = !{!"branch_weights", i32 5, i32 7}
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; CHECK-LABEL: @or
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; CHECK-LABEL: entry:
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; CHECK-NEXT: %cond.fr = freeze i1 %cond
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; CHECK-NEXT: br i1 %cond.fr, label %entry.split.us, label %entry.split, !prof !1
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; CHECK-LABEL: @and
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; CHECK-LABEL: entry:
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; CHECK-NEXT: %cond.fr = freeze i1 %cond
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; CHECK-NEXT: br i1 %cond.fr, label %entry.split, label %entry.split.us, !prof !3
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; CHECK: !1 = !{!"branch_weights", i32 1, i32 1000}
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; CHECK: !3 = !{!"unknown", !"simple-loop-unswitch"}
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;--- probable-and.prof
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!0 = !{!"function_entry_count", i32 10}
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!1 = !{!"branch_weights", i32 1000, i32 1}
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!2 = !{!"branch_weights", i32 5, i32 7}
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; CHECK-LABEL: @or
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; CHECK-LABEL: entry:
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; CHECK-NEXT: %cond.fr = freeze i1 %cond
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; CHECK-NEXT: br i1 %cond.fr, label %entry.split.us, label %entry.split, !prof !1
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; CHECK-LABEL: @and
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; CHECK-LABEL: entry:
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; CHECK-NEXT: %cond.fr = freeze i1 %cond
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; CHECK-NEXT: br i1 %cond.fr, label %entry.split, label %entry.split.us, !prof !3
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; CHECK: !1 = !{!"unknown", !"simple-loop-unswitch"}
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; CHECK: !3 = !{!"branch_weights", i32 1000, i32 1}
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