c752bb9203
When reviewing another change, I noticed that we were failing to infer samsign for two cases: 1) an unsigned comparison, and 2) when both arguments were known negative. Using CVP and InstCombine as a reference, we need to be careful to not allow eq/ne comparisons. I'm a bit unclear on the why of that, and for now am going with the low risk change. I may return to investigate that in a follow up. Compile time results look like noise to me, see: https://llvm-compile-time-tracker.com/compare.php?from=49a978712893fcf9e5f40ac488315d029cf15d3d&to=2ddb263604fd7d538e09dc1f805ebc30eb3ffab0&stat=instructions:u
47 lines
1.3 KiB
LLVM
47 lines
1.3 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
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; RUN: opt -S -passes=indvars < %s | FileCheck %s
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declare void @use(i1)
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; Make sure the division does not get expanded into the preheader.
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define i32 @test(i32 %arg) {
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; CHECK-LABEL: define i32 @test
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; CHECK-SAME: (i32 [[ARG:%.*]]) {
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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: br i1 false, label [[IF:%.*]], label [[LOOP_LATCH:%.*]]
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; CHECK: if:
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; CHECK-NEXT: [[DIV:%.*]] = udiv i32 7, [[ARG]]
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; CHECK-NEXT: [[CMP2:%.*]] = icmp samesign ult i32 1, [[DIV]]
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; CHECK-NEXT: call void @use(i1 [[CMP2]])
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; CHECK-NEXT: br label [[LOOP_LATCH]]
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; CHECK: loop.latch:
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; CHECK-NEXT: br i1 false, label [[LOOP]], label [[EXIT:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret i32 1
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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.latch ]
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%iv.next = add i32 %iv, 1
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%cmp = icmp eq i32 %iv, 1
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br i1 %cmp, label %if, label %loop.latch
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if:
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%div = udiv i32 7, %arg
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%cmp2 = icmp ult i32 %iv.next, %div
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call void @use(i1 %cmp2)
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br label %loop.latch
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loop.latch:
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br i1 false, label %loop, label %exit
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exit:
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%inc.lcssa = phi i32 [ %iv.next, %loop.latch ]
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ret i32 %inc.lcssa
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}
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