Add trap (an UDF instruction) to the ARM integrated Assembler.

src/IceAssemblerARM32.cpp

Index: src/IceAssemblerARM32.cpp
diff --git a/src/IceAssemblerARM32.cpp b/src/IceAssemblerARM32.cpp
index cbb5bdc71a3289ebb91684064331349ad89b6341..e8e9d141ecd752fa78c071b5618dd090f532a36a 100644
--- a/src/IceAssemblerARM32.cpp
+++ b/src/IceAssemblerARM32.cpp
@@ -1716,6 +1716,16 @@ void AssemblerARM32::sub(const Operand *OpRd, const Operand *OpRn,
              SubName);
 }
 
+// Use a particular UDF encoding -- TRAPNaCl in LLVM: 0xE7FEDEF0
+// http://llvm.org/viewvc/llvm-project?view=revision&revision=173943
+const uint8_t AssemblerARM32::TrapInst[4] = {0xE7, 0xFE, 0xDE, 0xF0};

[Jim Stichnoth, 2015/12/11 23:31:08]

I think you can omit the "4".

[Karl, 2015/12/17 16:23:09]

Done.

+
+void AssemblerARM32::trap() {
+  AssemblerBuffer::EnsureCapacity ensured(&Buffer);
+  for (size_t i = 1, len = llvm::array_lengthof(TrapInst); i <= len; ++i)

[Jim Stichnoth, 2015/12/11 23:31:08]

Hmm, I would use a "more familiar" form of the loop:

  for (i=0; i<len; ++i) { TrapInst[len-i-1] }

  for (i=len; i>0; --i) { TrapInst[i-1] }

[Karl, 2015/12/17 16:23:09]

Done.

+    Buffer.emit<uint8_t>(TrapInst[len - i]);
+}
+
 void AssemblerARM32::tst(const Operand *OpRn, const Operand *OpSrc1,
                          CondARM32::Cond Cond) {
   // TST (register) - ARM section A8.8.241, encoding A1: