Remove heaps from core Cranelift, push them into cranelift-wasm (#5386)

* cranelift-wasm: translate Wasm loads into lower-level CLIF operations

Rather than using `heap_{load,store,addr}`.

* cranelift: Remove the `heap_{addr,load,store}` instructions

These are now legalized in the `cranelift-wasm` frontend.

* cranelift: Remove the `ir::Heap` entity from CLIF

* Port basic memory operation tests to .wat filetests

* Remove test for verifying CLIF heaps

* Remove `heap_addr` from replace_branching_instructions_and_cfg_predecessors.clif test

* Remove `heap_addr` from readonly.clif test

* Remove `heap_addr` from `table_addr.clif` test

* Remove `heap_addr` from the simd-fvpromote_low.clif test

* Remove `heap_addr` from simd-fvdemote.clif test

* Remove `heap_addr` from the load-op-store.clif test

* Remove the CLIF heap runtest

* Remove `heap_addr` from the global_value.clif test

* Remove `heap_addr` from fpromote.clif runtests

* Remove `heap_addr` from fdemote.clif runtests

* Remove `heap_addr` from memory.clif parser test

* Remove `heap_addr` from reject_load_readonly.clif test

* Remove `heap_addr` from reject_load_notrap.clif test

* Remove `heap_addr` from load_readonly_notrap.clif test

* Remove `static-heap-without-guard-pages.clif` test

Will be subsumed when we port `make-heap-load-store-tests.sh` to generating
`.wat` tests.

* Remove `static-heap-with-guard-pages.clif` test

Will be subsumed when we port `make-heap-load-store-tests.sh` over to `.wat`
tests.

* Remove more heap tests

These will be subsumed by porting `make-heap-load-store-tests.sh` over to `.wat`
tests.

* Remove `heap_addr` from `simple-alias.clif` test

* Remove `heap_addr` from partial-redundancy.clif test

* Remove `heap_addr` from multiple-blocks.clif test

* Remove `heap_addr` from fence.clif test

* Remove `heap_addr` from extends.clif test

* Remove runtests that rely on heaps

Heaps are not a thing in CLIF or the interpreter anymore

* Add generated load/store `.wat` tests

* Enable memory-related wasm features in `.wat` tests

* Remove CLIF heap from fcmp-mem-bug.clif test

* Add a mode for compiling `.wat` all the way to assembly in filetests

* Also generate WAT to assembly tests in `make-load-store-tests.sh`

* cargo fmt

* Reinstate `f{de,pro}mote.clif` tests without the heap bits

* Remove undefined doc link

* Remove outdated SVG and dot file from docs

* Add docs about `None` returns for base address computation helpers

* Factor out `env.heap_access_spectre_mitigation()` to a local

* Expand docs for `FuncEnvironment::heaps` trait method

* Restore f{de,pro}mote+load clif runtests with stack memory

cranelift/codegen/src/settings.rs

@@ -518,9 +518,8 @@ mod tests {
     fn display_default() {
         let b = builder();
         let f = Flags::new(b);
-        assert_eq!(
-            f.to_string(),
-            r#"[shared]
+        let actual = f.to_string();
+        let expected = r#"[shared]
 opt_level = "none"
 tls_model = "none"
 libcall_call_conv = "isa_default"
@@ -537,7 +536,6 @@ avoid_div_traps = false
 enable_float = true
 enable_nan_canonicalization = false
 enable_pinned_reg = false
-use_pinned_reg_as_heap_base = false
 enable_simd = false
 enable_atomics = true
 enable_safepoints = false
@@ -551,8 +549,15 @@ enable_jump_tables = true
 enable_heap_access_spectre_mitigation = true
 enable_table_access_spectre_mitigation = true
 enable_incremental_compilation_cache_checks = false
-"#
-        );
+"#;
+        if actual != expected {
+            panic!(
+                "Default settings do not match expectations:\n\n{}",
+                similar::TextDiff::from_lines(expected, &actual)
+                    .unified_diff()
+                    .header("expected", "actual")
+            );
+        }
         assert_eq!(f.opt_level(), super::OptLevel::None);
         assert_eq!(f.enable_simd(), false);
     }