[PATCH] D59710: [SLP] remove lower limit for forming reduction patterns

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: llvm/test/Transforms/SLPVectorizer/X86/horizontal-list.ll:43
 ; THRESHOLD-NEXT:    [[CONV:%.*]] = sitofp i32 [[MUL]] to float
-; THRESHOLD-NEXT:    [[TMP1:%.*]] = load <2 x float>, <2 x float>* bitcast ([20 x float]* @arr to <2 x float>*), align 16
-; THRESHOLD-NEXT:    [[TMP2:%.*]] = load <2 x float>, <2 x float>* bitcast ([20 x float]* @arr1 to <2 x float>*), align 16
-; THRESHOLD-NEXT:    [[TMP3:%.*]] = fmul fast <2 x float> [[TMP2]], [[TMP1]]
-; THRESHOLD-NEXT:    [[TMP4:%.*]] = extractelement <2 x float> [[TMP3]], i32 0
-; THRESHOLD-NEXT:    [[ADD:%.*]] = fadd fast float [[TMP4]], [[CONV]]
-; THRESHOLD-NEXT:    [[TMP5:%.*]] = extractelement <2 x float> [[TMP3]], i32 1
-; THRESHOLD-NEXT:    [[ADD_1:%.*]] = fadd fast float [[TMP5]], [[ADD]]
-; THRESHOLD-NEXT:    [[TMP6:%.*]] = load <2 x float>, <2 x float>* bitcast (float* getelementptr inbounds ([20 x float], [20 x float]* @arr, i64 0, i64 2) to <2 x float>*), align 8
-; THRESHOLD-NEXT:    [[TMP7:%.*]] = load <2 x float>, <2 x float>* bitcast (float* getelementptr inbounds ([20 x float], [20 x float]* @arr1, i64 0, i64 2) to <2 x float>*), align 8
-; THRESHOLD-NEXT:    [[TMP8:%.*]] = fmul fast <2 x float> [[TMP7]], [[TMP6]]
-; THRESHOLD-NEXT:    [[TMP9:%.*]] = extractelement <2 x float> [[TMP8]], i32 0
-; THRESHOLD-NEXT:    [[ADD_2:%.*]] = fadd fast float [[TMP9]], [[ADD_1]]
-; THRESHOLD-NEXT:    [[TMP10:%.*]] = extractelement <2 x float> [[TMP8]], i32 1
-; THRESHOLD-NEXT:    [[ADD_3:%.*]] = fadd fast float [[TMP10]], [[ADD_2]]
+; THRESHOLD-NEXT:    [[TMP1:%.*]] = load float, float* getelementptr inbounds ([20 x float], [20 x float]* @arr, i64 0, i64 0), align 16
+; THRESHOLD-NEXT:    [[TMP2:%.*]] = load float, float* getelementptr inbounds ([20 x float], [20 x float]* @arr1, i64 0, i64 0), align 16
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ABataev wrote:
> What about this one? This also looks like a regression
Sanjay and I hve checked with godbolt/llvm-mca and this looks like a definite win (checked on bdver2, haswell and btver2). Top is scalar, middle is trunk and bottom is patched IR:

bdver2: https://godbolt.org/z/jwCPgI
haswell: https://godbolt.org/z/R-h8o_




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  https://reviews.llvm.org/D59710/new/

https://reviews.llvm.org/D59710