902ddda120
This adds a new pass for dropping assumes that are unlikely to be useful for further optimization. It works by discarding any assumes whose affected values are one-use (which implies that they are only used by the assume, i.e. ephemeral). This pass currently runs at the start of the module optimization pipeline, that is post-inline and post-link. Before that point, it is more likely for previously "useless" assumes to become useful again, e.g. because an additional user of the value is introduced after inlining + CSE.
26 lines
549 B
LLVM
26 lines
549 B
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -passes='default<O2>' -S < %s | FileCheck %s
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define void @PR45687(i32 %0) {
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; CHECK-LABEL: @PR45687(
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; CHECK-NEXT: ret void
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;
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%2 = add i32 %0, 1
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%3 = icmp ult i32 %2, 3
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tail call void @llvm.assume(i1 %3)
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%4 = icmp slt i32 %0, 0
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%5 = sub nsw i32 0, %0
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%6 = select i1 %4, i32 %5, i32 %0
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%7 = icmp sgt i32 %6, 1
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br i1 %7, label %8, label %9
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8:
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tail call void @g()
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br label %9
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9:
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ret void
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}
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declare void @llvm.assume(i1)
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declare void @g()
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