https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65304
Bug ID: 65304
Summary: [4.9] [ARM] incorrect "asm operand has impossible
constraints" error
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: cbaylis at gcc dot gnu.org
Target: arm-unknown-linux-gnueabihf
Created attachment 34940
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34940&action=edit
Original test case
The attached test case, and reduced variant result in an error: "asm operand
has impossible constraints". This is a regression since 4.8.
$ arm-unknown-linux-gnueabihf-gcc -O2 -S orig.c -mbig-endian -mthumb
-march=armv7-a -mtune=cortex-a8
orig.c: In function ‘rpc_print_iostats’:
orig.c:169:4: error: ‘asm’ operand has impossible constraints
asm ( "umlal %R0, %Q0, %R2, %Q3\n\t" \
^
orig.c:215:2: note: in expansion of macro ‘do_div’
do_div(t, 1000000);
^
-----
or
$ arm-unknown-linux-gnueabihf-gcc -O2 -S reduced.c -mbig-endian -mthumb
-march=armv7-a -mtune=cortex-a8
reduced.c: In function ‘fn2’:
reduced.c:26:7: error: ‘asm’ operand has impossible constraints
asm(" @asm2 %R0 %Q0 %R1 %R2 %Q2 %R3 %Q3" : "+&r"(n), "+&r"(q) :
"r"(o), "r"(p));
^
This does not occur on trunk, due to commit r209615:
2014-04-22 Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
* config/arm/arm.c (arm_hard_regno_mode_ok): Loosen
restrictions on core registers for DImode values in Thumb2.
However, since similar restrictions still exist in ARM state, it is possible
that there remains a latent bug on trunk.
This bug was originally reported in Linaro bugzilla
https://bugs.linaro.org/show_bug.cgi?id=1199
