This series introduces hard register constraints. The first patch
enables hard register constraints for asm statements and for
machine descriptions. The subsequent patch adds some basic error
handling for asm statements. The third patch adds some verification of
register names used in machine description. The fourth and last patch
adds the feature of rewriting local register asm into hard register
constraints.
This series was bootstrapped and regtested on s390. Furthermore, the
new dg-compile tests were verified via cross compilers for the enabled
targets. There is still some fallout if -fdemote-register-asm is used
since a couple of features are missing as e.g. erroring out during
gimplification if the clobber set of registers intersects with
input/output registers.
As a larger test vehicle I've compiled and regtested glibc on s390 using
-fdemote-register-asm without any fallout. On x86_64 this fails due to
the limitation that fixed registers are currently not supported for hard
register constraints (see commit message of the first patch). This is
also the reason why I'm posting this series already since I was hoping
to get some feedback about this limitation.
Furthermore, I've compiled the Linux kernel on s390 and x86_64 with
-fdemote-register-asm. Interestingly, the Linux kernel for x86_64 makes
use of the following asm statement:
#define call_on_stack(stack, func, asm_call, argconstr...) \
{ \
register void *tos asm("r11"); \
\
tos = ((void *)(stack)); \
\
asm_inline volatile( \
"movq %%rsp, (%[tos]) \n" \
"movq %[tos], %%rsp \n" \
\
asm_call \
\
"popq %%rsp \n" \
\
: "+r" (tos), ASM_CALL_CONSTRAINT \
: [__func] "i" (func), [tos] "r" (tos) argconstr \
: "cc", "rax", "rcx", "rdx", "rsi", "rdi", "r8", "r9", "r10", \
"memory" \
); \
}
Note the output
"+r" (tos)
and the input
[tos] "r" (tos)
Currently I error out for this since I consider this as two inputs using
the same hard register. One time an implicit input via '+' and a second
time via the explicit input. Thus, actually I would expect a '='
instead of a '+' for the output constraint since the input is explicitly
mentioned, or remove the input entirely and just use the inoutput
[tos] "+r" (tos)
If you consider this valid asm I would have to adjust the error
handling. Either way, this is just about error handling and doesn't
really affect code generation.
Stefan Schulze Frielinghaus (4):
Hard register constraints
Error handling for hard register constraints
genoutput: Verify hard register constraints
Rewrite register asm into hard register constraints
gcc/cfgexpand.cc | 42 ---
gcc/common.opt | 4 +
gcc/function.cc | 116 ++++++++
gcc/genoutput.cc | 60 ++++
gcc/genpreds.cc | 4 +-
gcc/gimplify.cc | 151 +++++++++-
gcc/gimplify_reg_info.h | 130 +++++++++
gcc/ira.cc | 79 +++++-
gcc/lra-constraints.cc | 13 +
gcc/output.h | 2 +
gcc/recog.cc | 11 +-
gcc/stmt.cc | 268 +++++++++++++++++-
gcc/stmt.h | 9 +-
gcc/testsuite/gcc.dg/asm-hard-reg-1.c | 85 ++++++
gcc/testsuite/gcc.dg/asm-hard-reg-2.c | 33 +++
gcc/testsuite/gcc.dg/asm-hard-reg-3.c | 25 ++
gcc/testsuite/gcc.dg/asm-hard-reg-4.c | 50 ++++
gcc/testsuite/gcc.dg/asm-hard-reg-5.c | 36 +++
gcc/testsuite/gcc.dg/asm-hard-reg-6.c | 60 ++++
gcc/testsuite/gcc.dg/asm-hard-reg-7.c | 41 +++
gcc/testsuite/gcc.dg/asm-hard-reg-8.c | 49 ++++
.../gcc.dg/asm-hard-reg-demotion-1.c | 19 ++
.../gcc.dg/asm-hard-reg-demotion-2.c | 19 ++
gcc/testsuite/gcc.dg/asm-hard-reg-demotion.h | 52 ++++
gcc/testsuite/gcc.dg/asm-hard-reg-error-1.c | 83 ++++++
gcc/testsuite/gcc.dg/asm-hard-reg-error-2.c | 20 ++
gcc/testsuite/gcc.dg/asm-hard-reg-error-3.c | 21 ++
gcc/testsuite/gcc.dg/pr87600-2.c | 30 +-
gcc/testsuite/gcc.dg/pr87600-3.c | 35 +++
gcc/testsuite/gcc.dg/pr87600-3.s | 0
.../gcc.target/s390/asm-hard-reg-1.c | 103 +++++++
.../gcc.target/s390/asm-hard-reg-2.c | 43 +++
.../gcc.target/s390/asm-hard-reg-3.c | 42 +++
gcc/testsuite/lib/scanasm.exp | 4 +
gcc/toplev.cc | 4 +
35 files changed, 1656 insertions(+), 87 deletions(-)
create mode 100644 gcc/gimplify_reg_info.h
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-1.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-2.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-3.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-4.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-5.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-6.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-7.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-8.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-demotion-1.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-demotion-2.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-demotion.h
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-error-1.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-error-2.c
create mode 100644 gcc/testsuite/gcc.dg/asm-hard-reg-error-3.c
create mode 100644 gcc/testsuite/gcc.dg/pr87600-3.c
create mode 100644 gcc/testsuite/gcc.dg/pr87600-3.s
create mode 100644 gcc/testsuite/gcc.target/s390/asm-hard-reg-1.c
create mode 100644 gcc/testsuite/gcc.target/s390/asm-hard-reg-2.c
create mode 100644 gcc/testsuite/gcc.target/s390/asm-hard-reg-3.c
--
2.45.2
