MdeModulePkg: Shortcircuit GCD Dumping Logic if Not Printing

CoreDumpGcdMemorySpaceMap() gets called on every update to
the GCD, but it only prints if DEBUG_GCD is set. However,
the compiler is not smart enough to remove all of this logic
if we are not printing anything, so we end up needlessly
allocating memory for the copy of the map and spending many
cycles looping through each entry, only to not print anything.

This code is compiled out on release builds, but slows down
debug builds that aren't printing at DEBUG_GCD level.

This patch updates CoreDumpGcdMemorySpaceMap() to shortcircuit
and immediately exit if DEBUG_GCD is not set. It also adds
the same logic to CoreDumpGcdIoSpaceMap(), which is called
less frequently, but has the same issue.

Signed-off-by: Oliver Smith-Denny <[email protected]>

Author: os-d

MdeModulePkg/Core/Dxe/Gcd/Gcd.c

@@ -153,6 +153,13 @@ CoreDumpGcdMemorySpaceMap (
   EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *MemorySpaceMap;
   UINTN                            Index;
 
+  // The compiler is not smart enough to compile out the whole function if DEBUG_GCD is not enabled, so we end up
+  // looping through the GCD every time it gets updated, which wastes a lot of needless cycles if we aren't going to
+  // print it. So shortcircuit and jump out if we don't need to print it.
+  if (!DebugPrintLevelEnabled (DEBUG_GCD)) {
+    return;
+  }
+
   Status = CoreGetMemorySpaceMap (&NumberOfDescriptors, &MemorySpaceMap);
   ASSERT (Status == EFI_SUCCESS && MemorySpaceMap != NULL);
 
@@ -199,6 +206,13 @@ CoreDumpGcdIoSpaceMap (
   EFI_GCD_IO_SPACE_DESCRIPTOR  *IoSpaceMap;
   UINTN                        Index;
 
+  // The compiler is not smart enough to compile out the whole function if DEBUG_GCD is not enabled, so we end up
+  // looping through the GCD every time it gets updated, which wastes a lot of needless cycles if we aren't going to
+  // print it. So shortcircuit and jump out if we don't need to print it.
+  if (!DebugPrintLevelEnabled (DEBUG_GCD)) {
+    return;
+  }
+
   Status = CoreGetIoSpaceMap (&NumberOfDescriptors, &IoSpaceMap);
   ASSERT (Status == EFI_SUCCESS && IoSpaceMap != NULL);