[RISCV][NFC] Document RISC-V-specific assembly constraints

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@368167 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/LangRef.rst b/docs/LangRef.rst
index abbd7941b5d82ed0aaa446545a8f5a2e26ce07e3..b6979e5fc2eaf1b8a84578ff8e3746cd01fcda9d 100644 (file)
--- a/docs/LangRef.rst
+++ b/docs/LangRef.rst
@@ -3952,6 +3952,17 @@ PowerPC:
 - ``ws``: A 32 or 64-bit floating-point register, from the full VSX register
   set.
 
+RISC-V:
+
+- ``A``: An address operand (using a general-purpose register, without an
+  offset).
+- ``I``: A 12-bit signed integer immediate operand.
+- ``J``: A zero integer immediate operand.
+- ``K``: A 5-bit unsigned integer immediate operand.
+- ``f``: A 32- or 64-bit floating-point register (requires F or D extension).
+- ``r``: A 32- or 64-bit general-purpose register (depending on the platform
+  ``XLEN``).
+
 Sparc:
 
 - ``I``: An immediate 13-bit signed integer.