skeleton for backend chapters

src/SUMMARY.md

@@ -101,10 +101,13 @@
     - [Constant evaluation](./const-eval.md)
         - [miri const evaluator](./miri.md)
     - [Parameter Environments](./param_env.md)
-    - [Code Generation](./codegen.md)
+    - [Compiler Backend](./backend/backend.md)
-        - [Updating LLVM](./codegen/updating-llvm.md)
+        - [Monomorphization](./backend/monomorph.md)
-        - [Debugging LLVM](./codegen/debugging.md)
+        - [Lowering MIR](./backend/lowering-mir.md)
-        - [Backend Agnostic Codegen](./codegen/backend-agnostic.md)
+        - [Code Generation](./backend/codegen.md)
+            - [Updating LLVM](./backend/updating-llvm.md)
+            - [Debugging LLVM](./backend/debugging.md)
+            - [Backend Agnostic Codegen](./backend/backend-agnostic.md)
         - [Profile-guided Optimization](./profile-guided-optimization.md)
         - [Sanitizers Support](./sanitizers.md)
         - [Debugging Support in Rust Compiler](./debugging-support-in-rustc.md)

src/backend/backend.md

@@ -0,0 +1 @@
+# The Compiler Backend

src/backend/codegen.md

@@ -6,7 +6,7 @@ generates an executable binary. rustc uses LLVM for code generation.
 > NOTE: If you are looking for hints on how to debug code generation bugs,
 > please see [this section of the debugging chapter][debugging].
 
-[debugging]: codegen/debugging.html
+[debugging]: ./debugging.md
 
 ## What is LLVM?
 

src/backend/debugging.md

@@ -3,7 +3,7 @@
 > NOTE: If you are looking for info about code generation, please see [this
 > chapter][codegen] instead.
 
-[codegen]: ../codegen.md
+[codegen]: ./codegen.md
 
 This section is about debugging compiler bugs in code generation (e.g. why the
 compiler generated some piece of code or crashed in LLVM).  LLVM is a big

src/backend/monomorph.md

@@ -0,0 +1 @@
+# Monomorphization

src/compiler-debugging.md

@@ -4,9 +4,8 @@
 This chapter contains a few tips to debug the compiler. These tips aim to be
 useful no matter what you are working on.  Some of the other chapters have
 advice about specific parts of the compiler (e.g. the [Queries Debugging and
-Testing
+Testing chapter](./incrcomp-debugging.html) or the [LLVM Debugging
-chapter](./incrcomp-debugging.html) or
+chapter](./backend/debugging.md)).
-the [LLVM Debugging chapter](./codegen/debugging.md)).
 
 ## `-Z` flags
 

src/ice-breaker/llvm.md

@@ -23,7 +23,7 @@ it useful to look at the various codegen options listed under `-Chelp`
 and the internal options under `-Zhelp` -- there are a number that
 pertain to LLVM (just search for LLVM).
 
-[d]: ../codegen/debugging.md
+[d]: ../backend/debugging.md
 
 ## If you do narrow to an LLVM bug