mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-15 20:29:48 +00:00
058309ba87
This commit makes LLVM not estimate branch probabilities when doing a
single bit bitmask tests.
The code that originally made me discover this is:
if ((a & 0x1) == 0x1) {
..
}
In this case we don't actually have any branch probability information
and should not assume to have any. LLVM transforms this into:
%and = and i32 %a, 1
%tobool = icmp eq i32 %and, 0
So, in this case, the result of a bitwise and is compared against 0,
but nevertheless, we should not assume to have probability
information.
CodeGen/ARM/2013-10-11-select-stalls.ll started failing because the
changed probabilities changed the results of
ARMBaseInstrInfo::isProfitableToIfCvt() and led to an Ifcvt of the
diamond in the test. AFAICT, the test was never meant to test this and
thus changing the test input slightly to not change the probabilities
seems like the best way to preserve the meaning of the test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234979 91177308-0d34-0410-b5e6-96231b3b80d8
243 lines
6.4 KiB
LLVM
243 lines
6.4 KiB
LLVM
; RUN: opt < %s -analyze -branch-prob | FileCheck %s
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define i32 @test1(i32 %i, i32* %a) {
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; CHECK: Printing analysis {{.*}} for function 'test1'
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entry:
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br label %body
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; CHECK: edge entry -> body probability is 16 / 16 = 100%
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body:
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%iv = phi i32 [ 0, %entry ], [ %next, %body ]
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%base = phi i32 [ 0, %entry ], [ %sum, %body ]
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%arrayidx = getelementptr inbounds i32, i32* %a, i32 %iv
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%0 = load i32, i32* %arrayidx
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%sum = add nsw i32 %0, %base
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%next = add i32 %iv, 1
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%exitcond = icmp eq i32 %next, %i
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br i1 %exitcond, label %exit, label %body
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; CHECK: edge body -> exit probability is 4 / 128
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; CHECK: edge body -> body probability is 124 / 128
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exit:
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ret i32 %sum
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}
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define i32 @test2(i32 %i, i32 %a, i32 %b) {
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; CHECK: Printing analysis {{.*}} for function 'test2'
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entry:
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%cond = icmp ult i32 %i, 42
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br i1 %cond, label %then, label %else, !prof !0
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; CHECK: edge entry -> then probability is 64 / 68
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; CHECK: edge entry -> else probability is 4 / 68
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then:
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br label %exit
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; CHECK: edge then -> exit probability is 16 / 16 = 100%
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else:
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br label %exit
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; CHECK: edge else -> exit probability is 16 / 16 = 100%
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exit:
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%result = phi i32 [ %a, %then ], [ %b, %else ]
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ret i32 %result
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}
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!0 = !{!"branch_weights", i32 64, i32 4}
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define i32 @test3(i32 %i, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) {
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; CHECK: Printing analysis {{.*}} for function 'test3'
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entry:
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switch i32 %i, label %case_a [ i32 1, label %case_b
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i32 2, label %case_c
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i32 3, label %case_d
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i32 4, label %case_e ], !prof !1
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; CHECK: edge entry -> case_a probability is 4 / 80
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; CHECK: edge entry -> case_b probability is 4 / 80
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; CHECK: edge entry -> case_c probability is 64 / 80
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; CHECK: edge entry -> case_d probability is 4 / 80
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; CHECK: edge entry -> case_e probability is 4 / 80
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case_a:
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br label %exit
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; CHECK: edge case_a -> exit probability is 16 / 16 = 100%
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case_b:
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br label %exit
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; CHECK: edge case_b -> exit probability is 16 / 16 = 100%
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case_c:
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br label %exit
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; CHECK: edge case_c -> exit probability is 16 / 16 = 100%
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case_d:
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br label %exit
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; CHECK: edge case_d -> exit probability is 16 / 16 = 100%
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case_e:
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br label %exit
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; CHECK: edge case_e -> exit probability is 16 / 16 = 100%
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exit:
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%result = phi i32 [ %a, %case_a ],
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[ %b, %case_b ],
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[ %c, %case_c ],
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[ %d, %case_d ],
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[ %e, %case_e ]
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ret i32 %result
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}
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!1 = !{!"branch_weights", i32 4, i32 4, i32 64, i32 4, i32 4}
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define i32 @test4(i32 %x) nounwind uwtable readnone ssp {
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; CHECK: Printing analysis {{.*}} for function 'test4'
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entry:
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%conv = sext i32 %x to i64
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switch i64 %conv, label %return [
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i64 0, label %sw.bb
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i64 1, label %sw.bb
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i64 2, label %sw.bb
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i64 5, label %sw.bb1
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], !prof !2
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; CHECK: edge entry -> return probability is 7 / 85
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; CHECK: edge entry -> sw.bb probability is 14 / 85
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; CHECK: edge entry -> sw.bb1 probability is 64 / 85
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sw.bb:
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br label %return
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sw.bb1:
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br label %return
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return:
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%retval.0 = phi i32 [ 5, %sw.bb1 ], [ 1, %sw.bb ], [ 0, %entry ]
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ret i32 %retval.0
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}
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!2 = !{!"branch_weights", i32 7, i32 6, i32 4, i32 4, i32 64}
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declare void @coldfunc() cold
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define i32 @test5(i32 %a, i32 %b, i1 %flag) {
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; CHECK: Printing analysis {{.*}} for function 'test5'
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entry:
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br i1 %flag, label %then, label %else
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; CHECK: edge entry -> then probability is 4 / 68
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; CHECK: edge entry -> else probability is 64 / 68
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then:
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call void @coldfunc()
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br label %exit
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; CHECK: edge then -> exit probability is 16 / 16 = 100%
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else:
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br label %exit
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; CHECK: edge else -> exit probability is 16 / 16 = 100%
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exit:
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%result = phi i32 [ %a, %then ], [ %b, %else ]
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ret i32 %result
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}
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declare i32 @regular_function(i32 %i)
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define i32 @test_cold_call_sites(i32* %a) {
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; Test that edges to blocks post-dominated by cold call sites
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; are marked as not expected to be taken.
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; TODO(dnovillo) The calls to regular_function should not be merged, but
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; they are currently being merged. Convert this into a code generation test
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; after that is fixed.
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; CHECK: Printing analysis {{.*}} for function 'test_cold_call_sites'
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; CHECK: edge entry -> then probability is 4 / 68 = 5.88235%
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; CHECK: edge entry -> else probability is 64 / 68 = 94.1176% [HOT edge]
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entry:
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%gep1 = getelementptr i32, i32* %a, i32 1
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%val1 = load i32, i32* %gep1
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%cond1 = icmp ugt i32 %val1, 1
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br i1 %cond1, label %then, label %else
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then:
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; This function is not declared cold, but this call site is.
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%val4 = call i32 @regular_function(i32 %val1) cold
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br label %exit
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else:
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%gep2 = getelementptr i32, i32* %a, i32 2
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%val2 = load i32, i32* %gep2
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%val3 = call i32 @regular_function(i32 %val2)
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br label %exit
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exit:
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%ret = phi i32 [ %val4, %then ], [ %val3, %else ]
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ret i32 %ret
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}
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define i32 @zero1(i32 %i, i32 %a, i32 %b) {
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; CHECK: Printing analysis {{.*}} for function 'zero1'
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entry:
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%cond = icmp eq i32 %i, 0
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br i1 %cond, label %then, label %else
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; CHECK: edge entry -> then probability is 12 / 32
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; CHECK: edge entry -> else probability is 20 / 32
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then:
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br label %exit
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else:
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br label %exit
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exit:
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%result = phi i32 [ %a, %then ], [ %b, %else ]
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ret i32 %result
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}
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define i32 @zero2(i32 %i, i32 %a, i32 %b) {
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; CHECK: Printing analysis {{.*}} for function 'zero2'
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entry:
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%cond = icmp ne i32 %i, -1
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br i1 %cond, label %then, label %else
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; CHECK: edge entry -> then probability is 20 / 32
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; CHECK: edge entry -> else probability is 12 / 32
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then:
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br label %exit
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else:
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br label %exit
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exit:
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%result = phi i32 [ %a, %then ], [ %b, %else ]
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ret i32 %result
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}
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define i32 @zero3(i32 %i, i32 %a, i32 %b) {
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; CHECK: Printing analysis {{.*}} for function 'zero3'
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entry:
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; AND'ing with a single bit bitmask essentially leads to a bool comparison,
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; meaning we don't have probability information.
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%and = and i32 %i, 2
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%tobool = icmp eq i32 %and, 0
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br i1 %tobool, label %then, label %else
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; CHECK: edge entry -> then probability is 16 / 32
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; CHECK: edge entry -> else probability is 16 / 32
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then:
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; AND'ing with other bitmask might be something else, so we still assume the
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; usual probabilities.
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%and2 = and i32 %i, 5
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%tobool2 = icmp eq i32 %and2, 0
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br i1 %tobool2, label %else, label %exit
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; CHECK: edge then -> else probability is 12 / 32
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; CHECK: edge then -> exit probability is 20 / 32
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else:
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br label %exit
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exit:
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%result = phi i32 [ %a, %then ], [ %b, %else ]
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ret i32 %result
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}
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