Non-extended inline assembly statements should have asmstrings interpreted

[llvmbot]

Bugzilla Link	924
Resolution	FIXED
Resolved on	Feb 22, 2010 12:49
Version	1.7
OS	All
Blocks	#1234
Reporter	LLVM Bugzilla Contributor

Extended Description

This is a reduction from the linux kernel (gcc is happy with it, llvm-gcc isn't):

void bar() {
asm volatile ("xorl %eax, %eax; movl %eax, %fs; movl %eax, %gs");
}

[llvmbot]

assigned to @lattner

[lattner]

After poking at this for a while, it turns out that GCC has special support for asms with no operands. Urg.

-Chris

[lattner]

Fixed. Testcase here:
Regression/CFrontend/2006-09-28-SimpleAsm.c

Patch here:

===============================================================

--- llvm-convert.cpp (revision 118365)
+++ llvm-convert.cpp (working copy)
@@ -2443,6 +2443,20 @@
tree str = ASM_STRING(exp);
if (TREE_CODE(str) == ADDR_EXPR) str = TREE_OPERAND(str, 0);

• // ASM_INPUT_P - This flag is set if this is a non-extended ASM, which means
• // that the asm string should not be interpreted, other than to escape $'s.
• if (ASM_INPUT_P(exp)) {
• const char *InStr = TREE_STRING_POINTER(str);
• std::string Result;
• while (1) {

•  switch (*InStr++) {
  

•  case 0: return Result;                 // End of string.
  

•  default: Result += InStr[-1]; break;   // Normal character.
  

•  case '$': Result += "$$"; break;       // Escape '$' characters.
  

•  }
  

• }
• }
• // Expand [name] symbolic operand names.
  str = resolve_asm_operand_names(str, ASM_OUTPUTS(exp), ASM_INPUTS(exp));

-Chris