https://llvm.org/bugs/show_bug.cgi?id=24232
Bug ID: 24232
Summary: [X86] Inline assembly operands don't work with
.intel_syntax
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: r...@google.com
CC: llvmbugs@cs.uiuc.edu, noloa...@gmail.com,
rafael.espind...@gmail.com, y...@tsoft.com
Classification: Unclassified
Consider this C code:
int mynegation(int r) {
__asm(".intel_syntax\n"
"negl %0\n"
: "=r"(r)
: "0"(r));
return r;
}
It gives this IR:
define i32 @mynegation(i32 %r) {
entry:
%0 = tail call i32 asm ".intel_syntax\0Anegl $0\0A",
"=r,0,~{dirflag},~{fpsr},~{flags}"(i32 %r)
ret i32 %0
}
Our inline asm operand support expands the $0 operand as '%ecx' and then
attempts to re-parse the inline assembly. This fails, because '%ecx' should not
have the percent in intel style assembly. We get this error:
<inline asm>:2:6: error: unknown token in expression
negl %ecx
^
Our current inline assembly support works by running the operands through the
old AsmPrinter infrastructure and then re-parsing with MC. If instead we could
teach the MC asm parser how to tolerate symbolic operands, we could fix this
problem without worrying about .intel_syntax directives.
Alternatively, we could hack the intel syntax parser to be OK with %. GCC
probably does this.
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