forked from OSchip/llvm-project
100 lines
2.4 KiB
LLVM
100 lines
2.4 KiB
LLVM
; RUN: opt < %s -correlated-propagation -S | FileCheck %s
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; CHECK-LABEL: @test1
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define void @test1(i32 %n) {
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entry:
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br label %for.cond
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for.cond: ; preds = %for.body, %entry
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%a = phi i32 [ %n, %entry ], [ %shr, %for.body ]
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%cmp = icmp sgt i32 %a, 1
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br i1 %cmp, label %for.body, label %for.end
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for.body: ; preds = %for.cond
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; CHECK: lshr i32 %a, 5
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%shr = ashr i32 %a, 5
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br label %for.cond
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for.end: ; preds = %for.cond
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ret void
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}
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;; Negative test to show transform doesn't happen unless n > 0.
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; CHECK-LABEL: @test2
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define void @test2(i32 %n) {
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entry:
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br label %for.cond
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for.cond: ; preds = %for.body, %entry
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%a = phi i32 [ %n, %entry ], [ %shr, %for.body ]
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%cmp = icmp sgt i32 %a, -2
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br i1 %cmp, label %for.body, label %for.end
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for.body: ; preds = %for.cond
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; CHECK: ashr i32 %a, 2
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%shr = ashr i32 %a, 2
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br label %for.cond
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for.end: ; preds = %for.cond
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ret void
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}
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;; Non looping test case.
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; CHECK-LABEL: @test3
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define void @test3(i32 %n) {
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entry:
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%cmp = icmp sgt i32 %n, 0
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br i1 %cmp, label %bb, label %exit
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bb:
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; CHECK: lshr exact i32 %n, 4
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%shr = ashr exact i32 %n, 4
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br label %exit
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exit:
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ret void
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}
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; looping case where loop has exactly one block
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; at the point of ashr, we know that the operand is always greater than 0,
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; because of the guard before it, so we can transform it to lshr.
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declare void @llvm.experimental.guard(i1,...)
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; CHECK-LABEL: @test4
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define void @test4(i32 %n) {
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entry:
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%cmp = icmp sgt i32 %n, 0
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br i1 %cmp, label %loop, label %exit
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loop:
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; CHECK: lshr i32 %a, 1
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%a = phi i32 [ %n, %entry ], [ %shr, %loop ]
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%cond = icmp sgt i32 %a, 2
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call void(i1,...) @llvm.experimental.guard(i1 %cond) [ "deopt"() ]
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%shr = ashr i32 %a, 1
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br i1 %cond, label %loop, label %exit
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exit:
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ret void
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}
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; same test as above with assume instead of guard.
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declare void @llvm.assume(i1)
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; CHECK-LABEL: @test5
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define void @test5(i32 %n) {
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entry:
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%cmp = icmp sgt i32 %n, 0
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br i1 %cmp, label %loop, label %exit
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loop:
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; CHECK: lshr i32 %a, 1
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%a = phi i32 [ %n, %entry ], [ %shr, %loop ]
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%cond = icmp sgt i32 %a, 4
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call void @llvm.assume(i1 %cond)
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%shr = ashr i32 %a, 1
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%loopcond = icmp sgt i32 %shr, 8
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br i1 %loopcond, label %loop, label %exit
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exit:
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ret void
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}
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