[bigint][ia32] Make bigint::Compare inlineable

Due to the limits of ia32's calling convention, being able to
avoid construction of "Digits" objects (thanks to inlining)
helps a lot for microbenchmarks.

Fixed: chromium:1192133
Change-Id: I5676640d96a99dc6422f3946c608bcc93ef222ba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2947410
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75028}

src/bigint/bigint.h

@@ -206,7 +206,18 @@ class Platform {
 // mechanism when it takes too long. These functions return a {Status} value.
 
 // Returns r such that r < 0 if A < B; r > 0 if A > B; r == 0 if A == B.
-int Compare(Digits A, Digits B);
+// Defined here to be inlineable, which helps ia32 a lot (64-bit platforms
+// don't care).
+inline int Compare(Digits A, Digits B) {
+  A.Normalize();
+  B.Normalize();
+  int diff = A.len() - B.len();
+  if (diff != 0) return diff;
+  int i = A.len() - 1;
+  while (i >= 0 && A[i] == B[i]) i--;
+  if (i < 0) return 0;
+  return A[i] > B[i] ? 1 : -1;
+}
 
 enum class Status { kOk, kInterrupted };
 

src/bigint/vector-arithmetic.cc

@@ -34,16 +34,5 @@ void SubAt(RWDigits Z, Digits X) {
   }
 }
 
-int Compare(Digits A, Digits B) {
-  A.Normalize();
-  B.Normalize();
-  int diff = A.len() - B.len();
-  if (diff != 0) return diff;
-  int i = A.len() - 1;
-  while (i >= 0 && A[i] == B[i]) i--;
-  if (i < 0) return 0;
-  return A[i] > B[i] ? 1 : -1;
-}
-
 }  // namespace bigint
 }  // namespace v8