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Date: Wed, 13 Aug 2014 13:22:07 +0200
Subject: Re: compiling musl on x86_64 linux with pcc

On Wed, Aug 13, 2014 at 12:25:01PM +0200, wrote:
> pcc -std=c99 -nostdinc -ffreestanding -fexcess-precision=standard -frounding-math -D_XOPEN_SOURCE=700 -I./arch/x86_64 -I./src/internal -I./include  -Os -pipe -fomit-frame-pointer -fno-unwind-tables -fno-asynchronous-unwind-tables -Wa,--noexecstack -Werror=implicit-function-declaration -Werror=implicit-int -Werror=pointer-sign -Werror=pointer-arith -fno-stack-protector  -c -o src/env/__init_tls.o src/env/__init_tls.c
> src/env/__init_tls.c:112: error: #else in non-conditional section
> error: XXXXXX/libexec/cpp terminated with status 1

FWIIW, looks like a limitation of the preprocessor in pcc:

#ifdef SYS_mmap2

becomes after -E

   __syscall(#ifdef SYS_mmap2 ....

works around easily by moving the conditional out of the parentheses:
--- src/env/__init_tls.c.ori    2014-08-13 12:56:35.389032321 +0200
+++ src/env/__init_tls.c        2014-08-13 12:58:49.852815255 +0200
@@ -91,14 +91,17 @@
        libc.tls_size = 2*sizeof(void *)+T.size+T.align+sizeof(struct pthread);
        if (libc.tls_size > sizeof builtin_tls) {
-               mem = (void *)__syscall(
 #ifdef SYS_mmap2
+               mem = (void *)__syscall(
+                       0, libc.tls_size, PROT_READ|PROT_WRITE,
+                       MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+               mem = (void *)__syscall(
                        0, libc.tls_size, PROT_READ|PROT_WRITE,
                        MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
                /* -4095...-1 cast to void * will crash on dereference anyway,
                 * so don't bloat the init code checking for error codes and
                 * explicitly calling a_crash(). */

Othwerwise, pcc does not look robust against arithmetic expressions:

pcc -std=c99 -nostdinc -ffreestanding -fexcess-precision=standard -frounding-math -D_XOPEN_SOURCE=700 -I./arch/x86_64 -I./src/internal -I./include  -Os -pipe -fomit-frame-pointer -fno-unwind-tables -fno-asynchronous-unwind-tables -Wa,--noexecstack -Werror=implicit-function-declaration -Werror=implicit-int -Werror=pointer-sign -Werror=pointer-arith -fno-stack-protector  -c -o src/math/asinhl.o src/math/asinhl.c
src/math/asinhl.c, line 25: compiler error: Cannot generate code, node 0x5be9e0 op TEMP
error: XXXXXXXX/libexec/ccom terminated with status 1

24:             /* |x| >= 2 */
25:             x = logl(2*x + 1/(sqrtl(x*x+1)+x));

I will check this one on the pcc list.


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