Index: docs/AMDGPUUsage.rst
===================================================================
--- docs/AMDGPUUsage.rst
+++ docs/AMDGPUUsage.rst
@@ -33,6 +33,31 @@
 The terminology in the table, aside from the region memory space, is from the
 OpenCL standard.
 
+Trap Handler ABI
+----------------
+The OS element of the target triple controls the trap handler behavior.
+
+HSA OS
+^^^^^^
+For the HSA OS, the AMDGPU back-end emits s_trap for llvm.trap/llvm.debugtrap.
+Runtime trap handler supports the s_trap instruction with the following codes.
+Currently the compiler only generates two of the codes, but the trap handler
+ABI nevertheless defines all 4 codes.
+
+   ===================== ============= ============================================
+   Name                  Trap Code     Trap Handler Inputs
+   ===================== ============= ============================================
+   TrapCodeBreakPoint    0             Used for debugger breakpoint. If debugger is not installed causes dispatch to be terminated and its associated queue put into the error state.
+   TrapCodeLLVMTrap      1             Used for llvm.trap..queue_ptr is in SGPR0-1. Causes dispatch to be terminated and its associated queue put into the error state.
+   TrapCodeLLVMDebugTrap 2             Used for llvm.debugtrap. queue_ptr is in SGPR0-1. If debugger not installed handled same as llvm.trap.
+   TrapCodeHSADebugTrap  3             Used for HSA DEBUGTRAP. queue_ptr is in SGPR0-1, the user code is in VGPR0.
+   ===================== ============= ============================================
+
+Non-HSA OS
+^^^^^^^^^^
+For Graphics, S_ENDPGM is generated for llvm.trap. S_NOP is generated for
+llvm.debugtrap together with a warning that there is no trap handler installed.
+
 
 Assembler
 =========
@@ -261,47 +286,6 @@
 
 For full list of supported instructions, refer to "Vector ALU instructions".
 
-Trap Handler ABI
-----------------
-The Trap Handler suppored is implemented differently based on the host OS. OS
-is obtained from the appropriate element of the target triple HSA OS:
-
-.. code-block:: c++
-
-  enum TrapHandlerAbi {
-    TrapHandlerAbiNone = 0,
-    TrapHandlerAbiHsa = 1
-  };
-
-  TrapHandlerAbi getTrapHandlerAbi() const {
-    return isAmdHsaOS() ? TrapHandlerAbiHsa : TrapHandlerAbiNone;
-  }
-
-For HSA OS, a trap handler is always enabled and that the following S_TRAP immediate
-operand codes are supported:
-
-.. code-block:: c++
-
-  enum TrapCode {
-    TrapCodeBreakPoint = 0,
-    TrapCodeLLVMTrap = 1,
-    TrapCodeLLVMDebugTrap = 2,
-    TrapCodeHSADebugTrap = 3
-  };
-
-- 0: Used for debugger breakpoint. If debugger is not installed causes dispatch
-  to be terminated and its associated queue put into the error state.
-- 1: Used for llvm.trap..queue_ptr is in SGPR0-1. Causes dispatch to be
-  terminated and its associated queue put into the error state.
-- 2: Used for llvm.debugtrap. queue_ptr is in SGPR0-1. If debugger not installed
-  handled same as llvm.trap.
-- 3: Used for HSA DEBUGTRAP. queue_ptr is in SGPR0-1, the user code is in VGPR0.
-
-Graphics
-^^^^^^^^
-For Graphics, S_ENDPGM is generated for llvm.trap. S_NOP is generated for
-llvm.debugtrap together with a warning that there is no trap handler installed.
-
 HSA Code Object Directives
 --------------------------