[codegen] Register conflict in arm macro assembler

{LoadFromConstantsTable} uses r7 as a temporary register. This can
conflict with the load destination register, so use another register in
this case.

R=jgruber@chromium.org
CC=tebbi@chromium.org

Bug: v8:10077
Change-Id: I3359f31ab4b17838464ee9bf0828308161fb9c0d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1985990
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65606}

src/codegen/arm/macro-assembler-arm.cc

@@ -132,16 +132,15 @@ void TurboAssembler::LoadFromConstantsTable(Register destination,
 
   Register reg = destination;
   if (could_clobber_ip) {
-    Push(r7);
-    reg = r7;
+    reg = destination != r7 ? r7 : r8;
+    Push(reg);
   }
 
   LoadRoot(reg, RootIndex::kBuiltinsConstantsTable);
   ldr(destination, MemOperand(reg, offset));
 
   if (could_clobber_ip) {
-    DCHECK_EQ(reg, r7);
-    Pop(r7);
+    Pop(reg);
   }
 }