Switch CARBON_CHECK to a format string API (#4285)

This switches `DCHECK` and `FATAL` as well.

The goal is to reduce the code size impact of these assertions so that
we can keep more of them enabled. Currently, the largest cost I see from
`CHECK` is not the actual check or the cold code itself, but actually
the failure to inline trivial functions due to the presence of the cold
code. This means that our goal isn't to reduce apparent code size in the
final binary but the LLVM IR cost assessed for these routines in the
inliner, which closely correlates with code size but is a bit different.

As discussed in #4283, experimentation shows that a single function call
with a minimal number of arguments is the lowest cost model for these.
This is easily achieved with a format-string API that internally uses
`llvm::formatv`. This PR is essentially the `CHECK` version of #4283.

However, the check macros are substantially harder to make work with
both format strings and streaming because they also take a condition.
Also, unexpectedly, I was very successful at devising a regular
expression based automated rewrite from the streaming to the format
string form with only low 10s of manual fixes. This includes compacting
strings broken up across lines, etc. Given how well that went, I've
prepared this PR which just directly switches to the format string API
and migrate everything to use it.

One nice side-effect is that the format string approach ends up greatly
simplifying the implementation here as well.

This is ... *shockingly* effective. Parsing speeds up by more than 3%
with just this change. And checking speeds up by **8%** with this change
alone:
```
BM_CompileAPIFileDenseDecls<Phase::Parse>/256      86.3µs ± 1%  82.9µs ± 1%  -3.94%  (p=0.000 n=17+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024      431µs ± 1%   415µs ± 1%  -3.76%  (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096     1.77ms ± 1%  1.71ms ± 1%  -3.18%  (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384    7.44ms ± 1%  7.17ms ± 2%  -3.56%  (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536    30.7ms ± 1%  29.7ms ± 1%  -3.15%  (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144    131ms ± 1%   127ms ± 1%  -2.81%  (p=0.000 n=18+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/256       878µs ± 2%   800µs ± 1%  -8.91%  (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/1024     1.88ms ± 2%  1.72ms ± 1%  -8.56%  (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/4096     5.78ms ± 2%  5.28ms ± 1%  -8.70%  (p=0.000 n=20+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/16384    21.9ms ± 1%  20.1ms ± 1%  -8.02%  (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/65536    90.4ms ± 2%  83.1ms ± 1%  -8.04%  (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/262144    381ms ± 2%   352ms ± 1%  -7.79%  (p=0.000 n=19+19)
```

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>

common/raw_hashtable.h

@@ -381,8 +381,8 @@ class ViewImpl {
   // given size. This is trivial, but we use this routine to enforce invariants
   // on the sizes.
   static constexpr auto EntriesOffset(ssize_t alloc_size) -> ssize_t {
-    CARBON_DCHECK(llvm::isPowerOf2_64(alloc_size))
-        << "Size must be a power of two for a hashed buffer!";
+    CARBON_DCHECK(llvm::isPowerOf2_64(alloc_size),
+                  "Size must be a power of two for a hashed buffer!");
     // The size is always a power of two. We prevent any too-small sizes so it
     // being a power of two provides the needed alignment. As a result, the
     // offset is exactly the size. We validate this here to catch alignment bugs
@@ -615,8 +615,8 @@ inline auto ComputeSeed() -> uint64_t {
 }
 
 inline auto ComputeProbeMaskFromSize(ssize_t size) -> size_t {
-  CARBON_DCHECK(llvm::isPowerOf2_64(size))
-      << "Size must be a power of two for a hashed buffer!";
+  CARBON_DCHECK(llvm::isPowerOf2_64(size),
+                "Size must be a power of two for a hashed buffer!");
   // Since `size` is a power of two, we can make sure the probes are less
   // than `size` by making the mask `size - 1`. We also mask off the low
   // bits so the probes are a multiple of the size of the groups of entries.
@@ -659,12 +659,14 @@ class ProbeSequence {
     // everything down by `GroupSize`.
     CARBON_DCHECK(
         (p_ / GroupSize) ==
-        ((start_ / GroupSize +
-          (step_ / GroupSize + (step_ / GroupSize) * (step_ / GroupSize)) / 2) %
-         (size_ / GroupSize)))
-        << "Index in probe sequence does not match the expected formula.";
-    CARBON_DCHECK(step_ < size_) << "We necessarily visit all groups, so we "
-                                    "can't have more probe steps than groups.";
+            ((start_ / GroupSize +
+              (step_ / GroupSize + (step_ / GroupSize) * (step_ / GroupSize)) /
+                  2) %
+             (size_ / GroupSize)),
+        "Index in probe sequence does not match the expected formula.");
+    CARBON_DCHECK(step_ < size_,
+                  "We necessarily visit all groups, so we can't have more "
+                  "probe steps than groups.");
 #endif
   }
 
@@ -924,13 +926,14 @@ auto BaseImpl<InputKeyT, InputValueT, InputKeyContextT>::InsertImpl(
     }
 
     --growth_budget_;
-    CARBON_DCHECK(growth_budget() >= 0)
-        << "Growth budget shouldn't have gone negative!";
+    CARBON_DCHECK(growth_budget() >= 0,
+                  "Growth budget shouldn't have gone negative!");
     return return_insert_at_index(group_index + empty_match.index());
   }
 
-  CARBON_FATAL() << "We should never finish probing without finding the entry "
-                    "or an empty slot.";
+  CARBON_FATAL(
+      "We should never finish probing without finding the entry or an empty "
+      "slot.");
 }
 
 template <typename InputKeyT, typename InputValueT, typename InputKeyContextT>
@@ -1264,11 +1267,11 @@ BaseImpl<InputKeyT, InputValueT, InputKeyContextT>::InsertIntoEmpty(
 template <typename InputKeyT, typename InputValueT, typename InputKeyContextT>
 auto BaseImpl<InputKeyT, InputValueT, InputKeyContextT>::ComputeNextAllocSize(
     ssize_t old_alloc_size) -> ssize_t {
-  CARBON_DCHECK(llvm::isPowerOf2_64(old_alloc_size))
-      << "Expected a power of two!";
+  CARBON_DCHECK(llvm::isPowerOf2_64(old_alloc_size),
+                "Expected a power of two!");
   ssize_t new_alloc_size;
   bool overflow = __builtin_mul_overflow(old_alloc_size, 2, &new_alloc_size);
-  CARBON_CHECK(!overflow) << "Computing the new size overflowed `ssize_t`!";
+  CARBON_CHECK(!overflow, "Computing the new size overflowed `ssize_t`!");
   return new_alloc_size;
 }
 
@@ -1340,11 +1343,10 @@ auto BaseImpl<InputKeyT, InputValueT, InputKeyContextT>::GrowToNextAllocSize(
       llvm::count(llvm::ArrayRef(old_metadata, old_size), MetadataGroup::Empty);
   ssize_t debug_deleted_count = llvm::count(
       llvm::ArrayRef(old_metadata, old_size), MetadataGroup::Deleted);
-  CARBON_DCHECK(debug_empty_count >=
-                (old_size - GrowthThresholdForAllocSize(old_size)))
-      << "debug_empty_count: " << debug_empty_count
-      << ", debug_deleted_count: " << debug_deleted_count
-      << ", size: " << old_size;
+  CARBON_DCHECK(
+      debug_empty_count >= (old_size - GrowthThresholdForAllocSize(old_size)),
+      "debug_empty_count: {0}, debug_deleted_count: {1}, size: {2}",
+      debug_empty_count, debug_deleted_count, old_size);
 #endif
 
   // Configure for the new size and allocate the new storage.