Initial version of a RiscV64g assembler.

There will be some issues and differences between this and
the standard RiscV assembler to be detailed later.

PiperOrigin-RevId: 715854881
Change-Id: I233b79c96c9c4cd6cf2516486f7964ef76d87fb7

mpact/sim/util/asm/simple_assembler.cc

diff --git a/mpact/sim/util/asm/simple_assembler.cc b/mpact/sim/util/asm/simple_assembler.cc
index 98c60c0..225452b 100644
--- a/mpact/sim/util/asm/simple_assembler.cc
+++ b/mpact/sim/util/asm/simple_assembler.cc
@@ -350,6 +350,8 @@
   SetTextSection(".text");
   SetDataSection(".data");
   SetBssSection(".bss");
+  // Clear the current section.
+  current_section_ = nullptr;
 }
 
 SimpleAssembler::~SimpleAssembler() {