[llvm] [SLP]Improved reduction cost/codegen (PR #118293)

[Alexey Bataev via llvm-commits]

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@@ -45,11 +45,19 @@ define float @test(ptr %x) {
 ; CHECK-NEXT:    [[TMP3:%.*]] = load float, ptr [[ARRAYIDX_28]], align 4
 ; CHECK-NEXT:    [[ARRAYIDX_29:%.*]] = getelementptr inbounds float, ptr [[X]], i64 30
 ; CHECK-NEXT:    [[TMP4:%.*]] = load float, ptr [[ARRAYIDX_29]], align 4
-; CHECK-NEXT:    [[TMP5:%.*]] = call fast float @llvm.vector.reduce.fadd.v16f32(float 0.000000e+00, <16 x float> [[TMP0]])
-; CHECK-NEXT:    [[TMP6:%.*]] = call fast float @llvm.vector.reduce.fadd.v8f32(float 0.000000e+00, <8 x float> [[TMP1]])
-; CHECK-NEXT:    [[OP_RDX:%.*]] = fadd fast float [[TMP5]], [[TMP6]]
-; CHECK-NEXT:    [[TMP7:%.*]] = call fast float @llvm.vector.reduce.fadd.v4f32(float 0.000000e+00, <4 x float> [[TMP2]])
-; CHECK-NEXT:    [[OP_RDX1:%.*]] = fadd fast float [[OP_RDX]], [[TMP7]]
+; CHECK-NEXT:    [[TMP5:%.*]] = call fast <4 x float> @llvm.vector.extract.v4f32.v16f32(<16 x float> [[TMP0]], i64 0)
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alexey-bataev wrote:

That's a good idea, will give it a try

https://github.com/llvm/llvm-project/pull/118293