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23f153bff9
The probability of edge coming to unreachable block should be as low as possible. The change reduces the probability to minimal value greater than zero. The bug https://bugs.llvm.org/show_bug.cgi?id=32214 show the example when the probability of edge coming to unreachable block is greater than for edge coming to out of the loop and it causes incorrect loop rotation. Please note that with this change the behavior of unreachable heuristic is a bit different than others. Specifically, before this change the sum of probabilities coming to unreachable blocks have the same weight for all branches (it was just split over all edges of this block coming to unreachable blocks). With this change it might be slightly different but not to much due to probability of taken branch to unreachable block is really small. Reviewers: chandlerc, sanjoy, vsk, congh, junbuml, davidxl, dexonsmith Reviewed By: chandlerc, dexonsmith Subscribers: reames, llvm-commits Differential Revision: https://reviews.llvm.org/D30633 llvm-svn: 303327
22 lines
649 B
LLVM
22 lines
649 B
LLVM
; RUN: opt -analyze -branch-prob < %s | FileCheck %s
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; RUN: opt < %s -passes='print<branch-prob>' -disable-output 2>&1 | FileCheck %s
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declare i32 @llvm.experimental.deoptimize.i32(...)
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define i32 @test1(i32 %a, i32 %b) {
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; CHECK-LABEL: Printing analysis {{.*}} for function 'test1':
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entry:
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%cond = icmp eq i32 %a, 42
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br i1 %cond, label %exit, label %deopt
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; CHECK: edge entry -> exit probability is 0x7fffffff / 0x80000000 = 100.00% [HOT edge]
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; CHECK: edge entry -> deopt probability is 0x00000001 / 0x80000000 = 0.00%
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deopt:
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%rval = call i32(...) @llvm.experimental.deoptimize.i32() [ "deopt"() ]
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ret i32 %rval
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exit:
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ret i32 %b
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}
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