[llvm] [LoopIdiom] Use narrower bit widths where possible in `optimizeCRCLoopUsingClmul` (PR #210139)

[Sean Clarke via llvm-commits]

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@@ -161,16 +161,17 @@ define i8 @crc8.le.tc16(i16 %msg, i8 %checksum) optsize {
 ; AES-LABEL: define i8 @crc8.le.tc16(
 ; AES-SAME: i16 [[MSG:%.*]], i8 [[CHECKSUM:%.*]]) #[[ATTR0]] {
 ; AES-NEXT:  [[ENTRY:.*:]]
-; AES-NEXT:    [[CRC_CAST:%.*]] = zext i8 [[CHECKSUM]] to i32
-; AES-NEXT:    [[DATA_CAST:%.*]] = zext i16 [[MSG]] to i32
-; AES-NEXT:    [[XOR_CRC_DATA1:%.*]] = xor i32 [[CRC_CAST]], [[DATA_CAST]]
-; AES-NEXT:    [[CRC_TCBITS:%.*]] = and i32 [[XOR_CRC_DATA1]], 65535
-; AES-NEXT:    [[CLMUL_MU:%.*]] = call i32 @llvm.clmul.i32(i32 [[CRC_TCBITS]], i32 24423)
+; AES-NEXT:    [[CRC_CAST:%.*]] = zext i8 [[CHECKSUM]] to i16
+; AES-NEXT:    [[XOR_CRC_DATA1:%.*]] = xor i16 [[CRC_CAST]], [[MSG]]
+; AES-NEXT:    [[TCBITS_CAST:%.*]] = zext i16 [[XOR_CRC_DATA1]] to i32
+; AES-NEXT:    [[CLMUL_MU:%.*]] = call i32 @llvm.clmul.i32(i32 [[TCBITS_CAST]], i32 24423)
 ; AES-NEXT:    [[QUOT_MASK:%.*]] = and i32 [[CLMUL_MU]], 65535
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xarkenz wrote:

This is now implemented.

https://github.com/llvm/llvm-project/pull/210139