commit 6650b0db52eee45f024652bae526ad64166ae02f
author Treehugger Robot <treehugger-gerrit@google.com> Tue Jan 23 20:45:36 2018 +0000
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Tue Jan 23 20:45:36 2018 +0000
tree c4a15d188f5e03d08d79957eb9cf0c84d8d56565
parent 49971eb50c0213b7506bdd29954a6a4423e6426a
parent 4eb45631b38445c587c235f1b2fa1699ba820e76

Merge "ARM: Use r4 for stack overflow check to reduce code size."

compiler/optimizing/code_generator_arm_vixl.cc

diff --git a/compiler/optimizing/code_generator_arm_vixl.cc b/compiler/optimizing/code_generator_arm_vixl.cc
index 84ba178..504c647 100644
--- a/compiler/optimizing/code_generator_arm_vixl.cc
+++ b/compiler/optimizing/code_generator_arm_vixl.cc
@@ -2490,8 +2490,12 @@
   }
 
   if (!skip_overflow_check) {
-    UseScratchRegisterScope temps(GetVIXLAssembler());
-    vixl32::Register temp = temps.Acquire();
+    // Using r4 instead of IP saves 2 bytes. Start by asserting that r4 is available here.
+    for (vixl32::Register reg : kParameterCoreRegistersVIXL) {
+      DCHECK(!reg.Is(r4));
+    }
+    DCHECK(!kCoreCalleeSaves.Includes(r4));
+    vixl32::Register temp = r4;
     __ Sub(temp, sp, Operand::From(GetStackOverflowReservedBytes(InstructionSet::kArm)));
     // The load must immediately precede RecordPcInfo.
     ExactAssemblyScope aas(GetVIXLAssembler(),