7 files changed, 69 insertions, 6 deletions
diff --git a/indra/cmake/00-Common.cmake b/indra/cmake/00-Common.cmake
index bb5dd8f847..3e672cb128 100644
--- a/indra/cmake/00-Common.cmake
+++ b/indra/cmake/00-Common.cmake
@@ -201,7 +201,7 @@ if (LINUX OR DARWIN)
   endif()
 
   if (NOT GCC_DISABLE_FATAL_WARNINGS)
-    set(GCC_WARNINGS "${GCC_WARNINGS} -Werror")
+    set(GCC_WARNINGS "${GCC_WARNINGS} -Werror -Wno-error=unused-but-set-variable")
   endif (NOT GCC_DISABLE_FATAL_WARNINGS)
 
   set(GCC_CXX_WARNINGS "${GCC_WARNINGS} -Wno-reorder -Wno-non-virtual-dtor")
diff --git a/indra/llcommon/llmemory.cpp b/indra/llcommon/llmemory.cpp
index 849867586a..267159e7cc 100644
--- a/indra/llcommon/llmemory.cpp
+++ b/indra/llcommon/llmemory.cpp
@@ -35,6 +35,7 @@
 # include <sys/types.h>
 # include <mach/task.h>
 # include <mach/mach_init.h>
+#include <mach/mach_host.h>
 #elif LL_LINUX
 # include <unistd.h>
 #endif
@@ -46,6 +47,9 @@
 #include "lltrace.h"
 #include "llerror.h"
 //----------------------------------------------------------------------------
+#if defined(LL_DARWIN)
+extern LLMemoryInfo gSysMemory;
+#endif
 
 //static
 U32Kilobytes LLMemory::sAvailPhysicalMemInKB(U32_MAX);
@@ -109,6 +113,51 @@ void LLMemory::updateMemoryInfo()
 	{
 		sAvailPhysicalMemInKB = U32Kilobytes(0);
 	}
+
+#elif defined(LL_DARWIN)
+    task_vm_info info;
+    mach_msg_type_number_t  infoCount = TASK_VM_INFO_COUNT;
+    // MACH_TASK_BASIC_INFO reports the same resident_size, but does not tell us the reusable bytes or phys_footprint.
+    if (task_info(mach_task_self(), TASK_VM_INFO, reinterpret_cast<task_info_t>(&info), &infoCount) == KERN_SUCCESS)
+    {
+        // Our Windows definition of PagefileUsage is documented by Microsoft as "the total amount of
+        // memory that the memory manager has committed for a running process", which is rss.
+        sAllocatedPageSizeInKB = U32Bytes(info.resident_size);
+
+        // Activity Monitor => Inspect Process => Real Memory Size appears to report resident_size
+        // Activity monitor => main window memory column appears to report phys_footprint, which spot checks as at least 30% less.
+        //        I think that is because of compression, which isn't going to give us a consistent measurement. We want uncompressed totals.
+        //
+        // In between is resident_size - reusable. This is what Chrome source code uses, with source comments saying it is 'the "Real Memory" value
+        // reported for the app by the Memory Monitor in Instruments.' It is still about 8% bigger than phys_footprint.
+        //
+        // (On Windows, we use WorkingSetSize.)
+        sAllocatedMemInKB = U32Bytes(info.resident_size - info.reusable);
+     }
+    else
+    {
+        LL_WARNS() << "task_info failed" << LL_ENDL;
+    }
+
+    // Total installed and available physical memory are properties of the host, not just our process.
+    vm_statistics64_data_t vmstat;
+    mach_msg_type_number_t count = HOST_VM_INFO64_COUNT;
+    mach_port_t host = mach_host_self();
+    vm_size_t page_size;
+    host_page_size(host, &page_size);
+    kern_return_t result = host_statistics64(host, HOST_VM_INFO64, reinterpret_cast<host_info_t>(&vmstat), &count);
+    if (result == KERN_SUCCESS) {
+        // This is what Chrome reports as 'the "Physical Memory Free" value reported by the Memory Monitor in Instruments.'
+        // Note though that inactive pages are not included here and not yet free, but could become so under memory pressure.
+        sAvailPhysicalMemInKB = U32Bytes(vmstat.free_count * page_size);
+
+        sMaxPhysicalMemInKB = gSysMemory.getPhysicalMemoryKB();
+      }
+    else
+    {
+        LL_WARNS() << "task_info failed" << LL_ENDL;
+    }
+
 #else
 	//not valid for other systems for now.
 	sAllocatedMemInKB = U64Bytes(LLMemory::getCurrentRSS());
diff --git a/indra/llwindow/llopenglview-objc.mm b/indra/llwindow/llopenglview-objc.mm
index fd20f2ad15..8d064ec86c 100644
--- a/indra/llwindow/llopenglview-objc.mm
+++ b/indra/llwindow/llopenglview-objc.mm
@@ -141,7 +141,12 @@ attributedStringInfo getSegments(NSAttributedString *str)
     CGLError the_err = CGLQueryRendererInfo (CGDisplayIDToOpenGLDisplayMask(kCGDirectMainDisplay), &info, &num_renderers);
     if(0 == the_err)
     {
-        CGLDescribeRenderer (info, 0, kCGLRPTextureMemoryMegabytes, &vram_megabytes);
+        // The name, uses, and other platform definitions of gGLManager.mVRAM suggest that this is supposed to be total vram in MB,
+        // rather than, say, just the texture memory. The two exceptions are:
+        // 1. LLAppViewer::getViewerInfo() puts the value in a field labeled "TEXTURE_MEMORY"
+        // 2. For years, this present function used kCGLRPTextureMemoryMegabytes
+        // Now we use kCGLRPVideoMemoryMegabytes to bring it in line with everything else (except thatone label).
+        CGLDescribeRenderer (info, 0, kCGLRPVideoMemoryMegabytes, &vram_megabytes);
         CGLDestroyRendererInfo (info);
     }
     else
diff --git a/indra/llwindow/llwindowmacosx.cpp b/indra/llwindow/llwindowmacosx.cpp
index bc4f07941b..4bcb9b3aef 100644
--- a/indra/llwindow/llwindowmacosx.cpp
+++ b/indra/llwindow/llwindowmacosx.cpp
@@ -1222,6 +1222,16 @@ F32 LLWindowMacOSX::getPixelAspectRatio()
 	return 1.f;
 }
 
+U32 LLWindowMacOSX::getAvailableVRAMMegabytes() {
+    // MTL (and MoltenVK) has some additional gpu data, such as recommendedMaxWorkingSetSize and currentAllocatedSize.
+    // But these are not available for OpenGL and/or our current mimimum OS version.
+    // So we will estimate.
+    static const U32 mb = 1024*1024;
+    // We're asked for total available gpu memory, but we only have allocation info on texture usage. So estimate by doubling that.
+    static const U32 total_factor = 2; // estimated total/textures
+    return gGLManager.mVRAM - (LLImageGL::getTextureBytesAllocated() * total_factor/mb);
+}
+
 //static SInt32 oldWindowLevel;
 
 // MBW -- XXX -- There's got to be a better way than this.  Find it, please...
diff --git a/indra/llwindow/llwindowmacosx.h b/indra/llwindow/llwindowmacosx.h
index 309d1377ea..0f316f1ddf 100644
--- a/indra/llwindow/llwindowmacosx.h
+++ b/indra/llwindow/llwindowmacosx.h
@@ -101,8 +101,7 @@ public:
 	void setNativeAspectRatio(F32 ratio) override { mOverrideAspectRatio = ratio; }
 
 	// query VRAM usage
-	// FIXME FIXME
-	virtual U32 getAvailableVRAMMegabytes() override { return 0; }
+    /*virtual*/ U32 getAvailableVRAMMegabytes() override;
 
 	void beforeDialog() override;
 	void afterDialog() override;
diff --git a/indra/newview/llviewertexture.cpp b/indra/newview/llviewertexture.cpp
index e31bc5ec6e..3584fffd44 100644
--- a/indra/newview/llviewertexture.cpp
+++ b/indra/newview/llviewertexture.cpp
@@ -524,7 +524,7 @@ void LLViewerTexture::getGPUMemoryForTextures(S32Megabytes &gpu, S32Megabytes &p
     {
         gpu_res = (S32Megabytes)gViewerWindow->getWindow()->getAvailableVRAMMegabytes();
         
-        //check main memory, only works for windows.
+        //check main memory, only works for windows and macos.
         LLMemory::updateMemoryInfo();
         physical_res = LLMemory::getAvailableMemKB();
 
diff --git a/indra/newview/llviewertexture.h b/indra/newview/llviewertexture.h
index 088d11538a..8c41c4a6bc 100644
--- a/indra/newview/llviewertexture.h
+++ b/indra/newview/llviewertexture.h
@@ -302,7 +302,7 @@ public:
 	};
 
 public:
-	/*virtual*/ S8 getType() const override ;
+	/*virtual*/ S8 getType() const override;
 	FTType getFTType() const;
 	/*virtual*/ void forceImmediateUpdate() override;
 	/*virtual*/ void dump() override;