C backend: inline asm - don't add rsp/esp to the clobber list

- it's deprecated in newer gcc versions and silently ignored in older versions
- gcc requires a valid stack to preserve registers and if the asm code clobbers esp/rsp
then there is no way to get it back after esp/rsp changes to something else.
- User is always responsoble for handling the stack registers.

Author: jayrm

changelog.txt

@@ -134,6 +134,7 @@ Version 1.08.0
 - C backend: switch to .text section after writing the exports to the C file in the explicit asm block.  gcc can move sections around with optimizations and there is a change between 7.x and 8.x that causes issue with where the directive section is located
 - sf.net #917: optimize 'm += s' string concatenations to fix the long compile times in the gcc backend (which makes heavy use of string building).
 - github #217: C backend, fix gcc array out of bounds warning when compiled with -O2 or higher optimizations and accessing non-zero lower bound fixed length string arrays
+- C backend: inline asm - don't add rsp/esp to the clobber list, it's deprecated in newer gcc versions and silently ignored in older versions 
 
 
 Version 1.07.0

src/compiler/ir-hlc.bas

@@ -3572,15 +3572,20 @@ private sub _emitAsmLine( byval asmtokenhead as ASTASMTOK ptr )
 			ln += " : " + inputconstraints
 
 			'' We don't know what registers etc. will be trashed,
-			'' so assume everything...
+			'' so assume everything... except for rsp/esp - gcc requires a valid
+			'' stack to preserve registers and if the asm code clobbers esp/rsp
+			'' then there is no way to get it back after esp/rsp changes to
+			'' something else.  User is always responsible for handling the stack
+			'' registers.
+			'' 
 			ln += " : ""cc"", ""memory"""
 
 			select case( fbGetCpuFamily( ) )
 			case FB_CPUFAMILY_X86, FB_CPUFAMILY_X86_64
 				if( fbGetCpuFamily( ) = FB_CPUFAMILY_X86 ) then
-					ln += ", ""eax"", ""ebx"", ""ecx"", ""edx"", ""esp"", ""edi"", ""esi"""
+					ln += ", ""eax"", ""ebx"", ""ecx"", ""edx"", ""edi"", ""esi"""
 				else
-					ln += ", ""rax"", ""rbx"", ""rcx"", ""rdx"", ""rsp"", ""rdi"", ""rsi"""
+					ln += ", ""rax"", ""rbx"", ""rcx"", ""rdx"", ""rdi"", ""rsi"""
 					ln += ", ""r8"", ""r9"", ""r10"", ""r11"", ""r12"", ""r13"", ""r14"", ""r15"""
 				end if