add ability to disable LLVM dependency at build time

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>

4 files changed, 51 insertions, 1 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 20e0b92..3ce82f7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,6 +33,9 @@ include_directories(${PCIACCESS_INCLUDE_DIR})
 find_package(LibDRM REQUIRED)
 include_directories(${LIBDRM_INCLUDE_DIR})
 
+if($ENV{UMR_NO_LLVM})
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DUMR_NO_LLVM")
+else()
 find_package(LLVM REQUIRED COMPONENTS all)
 include_directories(${LLVM_INCLUDE_DIR})
 
@@ -49,7 +52,7 @@ if(LLVM_CMAKE_DIR)
     MCDisassembler
   )
 endif()
-
+endif()
 
 set(REQUIRED_EXTERNAL_LIBS
   ${CURSES_LIBRARIES}
diff --git a/README b/README
index 1efd561..37e7f15 100644
--- a/README
+++ b/README
@@ -47,6 +47,11 @@ NOTE:  Allowing untrusted users access to umr may lead to system
 comprimises, instability, and hardware damage.  Do not setuid this
 tool on multi-user systems.
 
+NOTE:  You may disable LLVM dependencies by adding UMR_NO_LLVM to your
+environment.  e.g.,
+
+    $ UMR_NO_LLVM=1 cmake ../
+
 Running umr
 ------------
 
diff --git a/doc/sphinx/source/build.rst b/doc/sphinx/source/build.rst
index a2a54ac..96a1e42 100644
--- a/doc/sphinx/source/build.rst
+++ b/doc/sphinx/source/build.rst
@@ -75,3 +75,15 @@ Though keep in mind that this introduces a security vulnerability so you should
 and development machines and not deployed machines.
 
 At this point umr should be installed and can be invoked by running the command ‘umr’.  
+
+-----------------
+Optional Packages
+-----------------
+
+You may disable LLVM dependencies by adding UMR_NO_LLVM to your shell environment:
+
+::
+
+	$ UMR_NO_LLVM=1 cmake .
+
+This will disable shader disassembly and result in "..." being printed for all opcode decodes.
diff --git a/src/lib/lowlevel/linux/umr_shader_disasm.c b/src/lib/lowlevel/linux/umr_shader_disasm.c
index 82db478..d6e698b 100644
--- a/src/lib/lowlevel/linux/umr_shader_disasm.c
+++ b/src/lib/lowlevel/linux/umr_shader_disasm.c
@@ -23,6 +23,8 @@
  *
  */
 #include "umr.h"
+
+#ifndef UMR_NO_LLVM
 #include <llvm-c/Disassembler.h>
 #include <llvm-c/Target.h>
 
@@ -104,3 +106,31 @@ int umr_shader_disasm(struct umr_asic *asic,
 	LLVMDisasmDispose(disasm_ref);
 	return 0;
 }
+
+#else
+
+/**
+ * umr_shader_disasm - Diassemble a shader
+ *
+ * @inst:  Shader program
+ * @inst_bytes: number of bytes in shader
+ * @PC:  Shader address in virtual memory
+ * @disasm_text:	array of pointers that are assigned pointers
+ *					to disassembled shader.
+ */
+int umr_shader_disasm(struct umr_asic *asic,
+		     uint8_t *inst, unsigned inst_bytes,
+		     uint64_t PC,
+		     char ***disasm_text)
+{
+	unsigned x;
+
+	*disasm_text = calloc(inst_bytes/4, sizeof(**disasm_text));
+
+	for (x = 0; x < inst_bytes; x += 4) {
+		(*disasm_text)[x/4] = strdup("...");
+	}
+	return 0;
+}
+
+#endif