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[TableGen] Check for duplicate register tuple definitions. #95725

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Merged
merged 1 commit into from
Jun 25, 2024

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nvjle
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@nvjle nvjle commented Jun 16, 2024

Currently TableGen does not directly detect duplicate synthesized registers as can happen in this example:

def GPR128 : RegisterTuples<[sub0, sub1, sub2, sub3],
[(decimate (shl GPR32, 0), 1),
(decimate (shl GPR32, 1), 1),
(decimate (shl GPR32, 2), 1),
(decimate (shl GPR32, 3), 1)]>;

def GPR128_Aligned : RegisterTuples<[sub0, sub1, sub2, sub3],
[(decimate (shl GPR32, 0), 4),
(decimate (shl GPR32, 1), 4),
(decimate (shl GPR32, 2), 4),
(decimate (shl GPR32, 3), 4)]>;

TableGen does fail, but with an unrelated and difficult to understand error that happens downstream of tuple expansion:
"error: No SubRegIndex for R0_R1_R2_R3 in R0_R1_R2_R3".

This patch detects the problem directly during expansion and emits an error pointing the user to the actual issue:
"error: Register tuple redefines register 'R0_R1_R2_R3'".

Currently TableGen does not directly detect duplicate synthesized
registers as can happen in this example:

def GPR128 : RegisterTuples<[sub0, sub1, sub2, sub3],
                            [(decimate (shl GPR32, 0), 1),
                             (decimate (shl GPR32, 1), 1),
                             (decimate (shl GPR32, 2), 1),
                             (decimate (shl GPR32, 3), 1)]>;

def GPR128_Aligned : RegisterTuples<[sub0, sub1, sub2, sub3],
                                    [(decimate (shl GPR32, 0), 4),
                                     (decimate (shl GPR32, 1), 4),
                                     (decimate (shl GPR32, 2), 4),
                                     (decimate (shl GPR32, 3), 4)]>;

TableGen does fail, but with an unrelated and difficult to understand
error that happens downstream of tuple expansion:
"error: No SubRegIndex for R0_R1_R2_R3 in R0_R1_R2_R3".

This patch detects the problem directly during expansion and emits an
error pointing the user to the actual issue:
"error: Register tuple redefines register 'R0_R1_R2_R3'".
@nvjle nvjle requested review from topperc and kazutakahirata June 17, 2024 00:15
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nvjle commented Jun 25, 2024

Any comments on this tiny patch? It is almost NFC, but it does do more specific error checking, so I'm treating it as a functional change for good measure. The failures are not due to this patch.

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LGTM

@nvjle nvjle merged commit edf5782 into llvm:main Jun 25, 2024
6 of 8 checks passed
AlexisPerry pushed a commit to llvm-project-tlp/llvm-project that referenced this pull request Jul 9, 2024
Currently TableGen does not directly detect duplicate synthesized
registers as can happen in this example:

def GPR128 : RegisterTuples<[sub0, sub1, sub2, sub3],
                            [(decimate (shl GPR32, 0), 1),
                             (decimate (shl GPR32, 1), 1),
                             (decimate (shl GPR32, 2), 1),
                             (decimate (shl GPR32, 3), 1)]>;

def GPR128_Aligned : RegisterTuples<[sub0, sub1, sub2, sub3],
                                    [(decimate (shl GPR32, 0), 4),
                                     (decimate (shl GPR32, 1), 4),
                                     (decimate (shl GPR32, 2), 4),
                                     (decimate (shl GPR32, 3), 4)]>;

TableGen does fail, but with an unrelated and difficult to understand
error that happens downstream of tuple expansion:
"error: No SubRegIndex for R0_R1_R2_R3 in R0_R1_R2_R3".

This patch detects the problem directly during expansion and emits an
error pointing the user to the actual issue:
"error: Register tuple redefines register 'R0_R1_R2_R3'".
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2 participants