[llvm] [RISCV][TTI] Cost non-power-of-two size changing casts (PR #101047)

[Philip Reames via llvm-commits]

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@@ -4317,24 +4317,24 @@ define void @uitofp() {
 
 define void @oddvec_sizes() {
 ; CHECK-LABEL: 'oddvec_sizes'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 9 for instruction: %1 = sext <3 x i8> undef to <3 x i16>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 21 for instruction: %2 = sext <7 x i8> undef to <7 x i32>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 45 for instruction: %3 = sext <15 x i8> undef to <15 x i32>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 9 for instruction: %4 = zext <3 x i8> undef to <3 x i16>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 21 for instruction: %5 = zext <7 x i8> undef to <7 x i32>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 45 for instruction: %6 = zext <15 x i8> undef to <15 x i32>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 6 for instruction: %7 = trunc <3 x i32> undef to <3 x i8>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 14 for instruction: %8 = trunc <7 x i32> undef to <7 x i8>
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 30 for instruction: %9 = trunc <15 x i32> undef to <15 x i8>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %1 = sext <3 x i8> undef to <3 x i16>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %2 = sext <7 x i8> undef to <7 x i32>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %3 = sext <15 x i8> undef to <15 x i32>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %4 = zext <3 x i8> undef to <3 x i16>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %5 = zext <7 x i8> undef to <7 x i32>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %6 = zext <15 x i8> undef to <15 x i32>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %7 = trunc <3 x i32> undef to <3 x i8>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %8 = trunc <7 x i32> undef to <7 x i8>
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 3 for instruction: %9 = trunc <15 x i32> undef to <15 x i8>
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preames wrote:

This exposes a bug in the base costing for truncs - we're using the destination LMUL where we should be using the source LMUL (since it's wider).  Will fix that separately.  

For the fp<->int cases a few lines below, that's the known lack of LMUL in the cost model.  See https://github.com/llvm/llvm-project/pull/87506

https://github.com/llvm/llvm-project/pull/101047