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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The code that originally made me discover this is: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
17 lines
653 B
LLVM
17 lines
653 B
LLVM
; REQUIRES: asserts
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; RUN: llc < %s -mtriple=thumbv7-apple-ios -stats 2>&1 | not grep "Number of pipeline stalls"
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; Evaluate the two vld1.8 instructions in separate MBB's,
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; instead of stalling on one and conditionally overwriting its result.
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define <16 x i8> @multiselect(i32 %avail, i8* %foo, i8* %bar) {
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entry:
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%vld1 = call <16 x i8> @llvm.arm.neon.vld1.v16i8(i8* %foo, i32 1)
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%vld2 = call <16 x i8> @llvm.arm.neon.vld1.v16i8(i8* %bar, i32 1)
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%and = and i32 %avail, 3
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%tobool = icmp eq i32 %and, 0
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%retv = select i1 %tobool, <16 x i8> %vld1, <16 x i8> %vld2
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ret <16 x i8> %retv
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}
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declare <16 x i8> @llvm.arm.neon.vld1.v16i8(i8* , i32 )
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