[llvm] [Analysis] Assign a CodeSize cost of 1 for division instructions rather than TTI::TCC_Expensive (PR #176524)

[Matt Arsenault via llvm-commits]

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@@ -50,22 +50,22 @@ define i32 @sdiv() {
 ; SLOW-NEXT:  Cost Model: Found an estimated cost of 10 for instruction: ret i32 undef
 ;
 ; ALL-SIZE-LABEL: 'sdiv'
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %I64 = sdiv i64 undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V2i64 = sdiv <2 x i64> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V4i64 = sdiv <4 x i64> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V8i64 = sdiv <8 x i64> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %I32 = sdiv i32 undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V4i32 = sdiv <4 x i32> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V8i32 = sdiv <8 x i32> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V16i32 = sdiv <16 x i32> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %I16 = sdiv i16 undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V8i16 = sdiv <8 x i16> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V16i16 = sdiv <16 x i16> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V32i16 = sdiv <32 x i16> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %I8 = sdiv i8 undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V16i8 = sdiv <16 x i8> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V32i8 = sdiv <32 x i8> undef, undef
-; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V64i8 = sdiv <64 x i8> undef, undef
+; ALL-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %I64 = sdiv i64 undef, undef
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arsenm wrote:

This is significantly undercounting the code size. The expansion for division is gigantic 

https://github.com/llvm/llvm-project/pull/176524