https://bugs.llvm.org/show_bug.cgi?id=42539
Bug ID: 42539
Summary: ARM:out of range pc-relative fixup value
Product: clang
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: -New Bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected], [email protected]
A file in the linux kernel got compiled into an invalid assembler output. I
reduced this to:
$ clang-9 -std=gnu89 --target=arm-linux-gnueabi -fsanitize=kernel-address -O2
-Wall -Wno-unused-value -Wno-parentheses-equality
-Wno-unused-command-line-argument -Wno-ignored-optimization-argument
/tmp/z-4fd29d.s:33: Error: bad immediate value for offset (4104)
typedef struct { long x[4 * 8 / 2]; } map_word;
struct {
void (*write)();
} g;
struct flchip {
long start;
int state;
} __attribute__((__packed__));
int a, b, c;
int fn2(void);
struct flchip d, h;
map_word e, f;
void fn1() {
g.write(e, h.start);
g.write(g, f, h.start);
while (({
for (; b;)
;
c;
}))
a = fn2();
asm(".rep 6; nop; .endr");
while (d.state)
;
}
See also https://godbolt.org/z/DSM2Jy
It seems that clang when clang tries to guess the size of the instructions in
an inline assembly, it gets the '.rep' statement wrong and assumes a smaller
number. Replacing ".rep 6; nop; .endr" with six straight nop instructions
avoids the problem.
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