Hello,
I am doing a preliminary analysis for supporting call frame debugging
information in avr. (gcc bug 17994). When I build, I am facing ICE in
dwarf2out. Obviously the code goes to gcc_unreachable() in the big function:
dwarf2out_frame_debug_expr(). Before I proceed further, I would like to know if
the call-stack information presented is correct.
I am posting little about the design, patch and error. Version of gcc I am
using is 4.4.3 (that got released with AVR Toolchain 3.0.0)
Little about design:
As per gcc internals, INCOMING_RETURN_ADDR_RTX should defined. Since AVR does
not have link register, the resulting address should be obtained from stack
top. I define INCOMING_RETURN_ADDR_RTX to avr_incoming_return_addr_rtx() in
avr.h which inturn is defined in avr.c as follows:
+
+/*Call stack information. Implements INCOMING_RETURN_ADDR_RTX
+
+ +-------------------------------+ <--- Frame Pointer(FP) for this frame
+ | local variables |
+ |-------------------------------|
+ |caller frame's frame pointer |
+ |-------------------------------|
+ | Return address |
+ +-------------------------------+
+
+*/
+
+rtx
+avr_incoming_return_addr_rtx (void)
+{
+ /* Compute return address which is stored on the stack.
+ Current stack pointer at the begining of frame, before the prologue
+ execution holds the return address. So our job is done if we get
+ the stack pointer register value which inturn points to return address
+ */
+ return gen_rtx_MEM (HImode, stack_pointer_rtx);
+}
+
+
ICE Error:
<snip> ... -g -O2 -mmcu=avr25 -O2 -g -O2 -DIN_GCC -DCROSS_DIRECTORY_STRUCTURE
-W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wcast-qual
-Wold-style-definition -isystem ./include -DDF=SF -Dinhibit_libc
-mcall-prologues -Os -g -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED -Dinhibit_libc
-I. -I. -I../../.././gcc -I../../../../libgcc -I../../../../libgcc/.
-I../../../../libgcc/../gcc -I../../../../libgcc/../include -o _mulvhi3.o -MT
_mulvhi3.o -MD -MP -MF _mulvhi3.dep -DL_mulvsi3 -c
../../../../libgcc/../gcc/libgcc2.c \
-DLIBGCC2_UNITS_PER_WORD=2
../../../../libgcc/../gcc/libgcc2.c: In function '__mulvhi3':
../../../../libgcc/../gcc/libgcc2.c:165: internal compiler error: in
dwarf2out_frame_debug_expr, at dwarf2out.c:2323
Please submit a full bug report,
Thanks
Anitha
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