[MC] [IAS] Add support for the \@ .macro pseudo-variable.

Summary:
When used, it is substituted with the number of .macro instantiations we've done up to that point in time.
So if this is the 1st time we've instantiated a .macro (any .macro, regardless of name), \@ will instantiate to 0, if it's the 2nd .macro instantiation, it will instantiate to 1 etc.

It can only be used inside a .macro definition, an .irp definition or an .irpc definition (those last 2 uses are undocumented).

Reviewers: echristo, rafael

Reviewed By: rafael

Subscribers: dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D9197

llvm-svn: 235862

1 files changed, 64 insertions, 0 deletions

diff --git a/llvm/test/MC/AsmParser/at-pseudo-variable.s b/llvm/test/MC/AsmParser/at-pseudo-variable.s
new file mode 100644
index 00000000000..b0966e13717
--- /dev/null
+++ b/llvm/test/MC/AsmParser/at-pseudo-variable.s
@@ -0,0 +1,64 @@
+# RUN: llvm-mc -triple i386-unknown-unknown %s | FileCheck %s
+
+.macro A
+  add  $1\@, %eax
+.endm
+
+.macro B
+  sub  $1\@, %eax
+.endm
+
+  A
+# CHECK: addl  $10, %eax
+  A
+# CHECK: addl  $11, %eax
+  B
+# CHECK: subl  $12, %eax
+  B
+# CHECK: subl  $13, %eax
+
+# The following uses of \@ are undocumented, but valid:
+.irpc foo,234
+  add  $\foo\@, %eax
+.endr
+# CHECK: addl  $24, %eax
+# CHECK: addl  $34, %eax
+# CHECK: addl  $44, %eax
+
+.irp reg,%eax,%ebx
+  sub  $2\@, \reg
+.endr
+# CHECK: subl  $24, %eax
+# CHECK: subl  $24, %ebx
+
+# Test that .irp(c) and .rep(t) do not increase \@.
+# Only the use of A should increase \@, so we can test that it increases by 1
+# each time.
+
+.irpc foo,123
+  sub  $\foo, %eax
+.endr
+
+  A
+# CHECK: addl  $14, %eax
+
+.irp reg,%eax,%ebx
+  sub  $4, \reg
+.endr
+
+  A
+# CHECK: addl  $15, %eax
+
+.rept 2
+  sub  $5, %eax
+.endr
+
+  A
+# CHECK: addl  $16, %eax
+
+.rep 3
+  sub  $6, %eax
+.endr
+
+  A
+# CHECK: addl  $17, %eax