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authorKyrylo Tkachov <kyrylo.tkachov@arm.com>2022-11-30 17:38:16 +0000
committerKyrylo Tkachov <kyrylo.tkachov@arm.com>2022-11-30 17:38:16 +0000
commitcbdffae5745327b0e5eb887afc512daf34b049b1 (patch)
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parent031d3f095520f0e1ee03e29b7ad5067c2a3f96e0 (diff)
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aarch64: Specify that FEAT_MOPS sequences clobber CC
According to the architecture pseudocode the FEAT_MOPS sequences overwrite the NZCV flags as par of their operation, so GCC needs to model that in the relevant RTL patterns. For the testcase: void g(); void foo (int a, size_t N, char *__restrict__ in, char *__restrict__ out) { if (a != 3) __builtin_memcpy (out, in, N); if (a > 3) g (); } we will currently generate: foo: cmp w0, 3 bne .L6 .L1: ret .L6: cpyfp [x3]!, [x2]!, x1! cpyfm [x3]!, [x2]!, x1! cpyfe [x3]!, [x2]!, x1! ble .L1 // Flags reused after CPYF* sequence b g This is wrong as the result of cmp needs to be recalculated after the MOPS sequence. With this patch we'll insert a "cmp w0, 3" before the ble, similar to what clang does. Bootstrapped and tested on aarch64-none-linux-gnu. Pushing to trunk and to the GCC 12 branch after some baking time. gcc/ChangeLog: * config/aarch64/aarch64.md (aarch64_cpymemdi): Specify clobber of CC reg. (*aarch64_cpymemdi): Likewise. (aarch64_movmemdi): Likewise. (aarch64_setmemdi): Likewise. (*aarch64_setmemdi): Likewise. gcc/testsuite/ChangeLog: * gcc.target/aarch64/mops_5.c: New test. * gcc.target/aarch64/mops_6.c: Likewise. * gcc.target/aarch64/mops_7.c: Likewise.
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