Modify arg passing info for struct with one int and one fp to match GCC behavior. #74
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For the reasons you state, I think this is the pragmatic path forwards. Perhaps we should have a changelog or errata section so it will be obvious to people reading the document that this detail recently changed? |
palmer-dabbelt
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I updated the patch. |
asb
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…t+fp structs for the FP ABI Pull request riscv-non-isa#74 clarified that when an int+fp struct is passed in a GPR+FPR in the floating point ABI, the integer isn't extended to XLEN (i.e. it is anyext, just as if it were passed on the stack). Unfortunately, a previous part of the sentence which mandated sign/zero-extension was left in. This patch removes the contradictory information.
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…t+fp structs for the FP ABI (#89) Pull request #74 clarified that when an int+fp struct is passed in a GPR+FPR in the floating point ABI, the integer isn't extended to XLEN (i.e. it is anyext, just as if it were passed on the stack). Unfortunately, a previous part of the sentence which mandated sign/zero-extension was left in. This patch removes the contradictory information.
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This is in response to an FSF GCC bug report
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86387
which states that GCC doesn't match the ABi in the handling of structs with one int and one fp real.
Unfortunately, addressing this in GCC would cause a non-backward compatible ABI break, and we promised that the ABI would not change when we upstreamed glibc in February. So we instead have to fix this in the ABI.