RFR: 8294715: Add IR checks to the reduction vectorization tests

[Emanuel Peter]

On Tue, 21 Feb 2023 08:08:31 GMT, Daniel Skantz <duke at openjdk.org> wrote:

> We are lifting some loopopts/superword tests to use the IR framework, and add IR annotations to check that vector reductions take place on x86_64. This can be useful to prevent issues such as JDK-8300865.
> 
> Approach: lift the more general tests in loopopts/superword, mainly using matching rules in cpu/x86/x86.ad, but leave tests mostly unchanged otherwise. Some reductions are considered non-profitable (superword.cpp), so we might need to raise sse/avx value pre-conditions from what would be a strict reading of x86.ad (as noted by @eme64).
> 
> Testing: Local testing (x86_64) using UseSSE={2,3,4}, UseAVX={0,1,2,3}. Tested running all jtreg compiler tests. Tier1-tier5 runs to my knowledge never showed any compiler-related regression in other tests as a result from this work. GHA. Validation: all tests fail if we put unreasonable counts for the respective reduction node, such as counts = {IRNode.ADD_REDUCTION_VI, ">= 10000000"}).
> 
> Thanks @robcasloz  and @eme64 for advice.
> 
> Notes: ProdRed_Double does not vectorize (JDK-8300865). SumRed_Long does not vectorize on 32-bit, according to my reading of source, test on GHA and cross-compiled JDK on 32-bit Linux, so removed these platforms from @requires. Lifted the AbsNeg tests too but added no checks, as these are currently not run on x86_64.

test/hotspot/jtreg/compiler/loopopts/superword/RedTest_long.java line 166:

> 164:     @IR(applyIf = {"SuperWordReductions", "false"},
> 165:         failOn = {IRNode.OR_REDUCTION_V})
> 166:     @IR(applyIfCPUFeature = {"avx2", "true"},

Add a comment why we only require `AVX2`. Add "negative" rule when not present.

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PR: https://git.openjdk.org/jdk/pull/12683