gfxstream: cereal: fix 'None' in gfxstream codegen

Commit e27e41a842 ("vulkan,spirv: update headers") exposed a
flaw in the cerealgenerator.

It modified -- among other things -- the VkDeviceCreateInfo
struct in vk.xml.

In the update, the len="enabledLayerCount,null-terminated"
attribute was removed from the ppEnabledLayerNames member.

The gfxstream code generator processes ppEnabledLayerNames
(which is a const char* const*), it identifies it as an "array of
strings". However, because the len attribute is now missing,
vulkanType.getLengthExpression() returns None.

This leads to errors like:

gfxstream_guest_vk_autogen_impl/gen/goldfish_vk_counting_guest.cpp:642:30:
error: use of undeclared identifier 'None'

     642 |     for (uint32_t i = 0; i < None; ++i)
         |                              ^~~~
   1 error generated.

This patch adds various length access checks to prevent this from
happening.

TEST=m vulkan.ranchu

Reviewed-by: David Gilhooley <djgilhooley@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40785>

src/gfxstream/codegen/scripts/cereal/counting.py

@@ -370,6 +370,7 @@ class VulkanCountingCodegen(VulkanTypeIterator):
         lenAccessGuard = self.lenAccessorGuard(vulkanType)
 
         self.genCount("sizeof(uint32_t)")
+        if lenAccess is not None:
             if lenAccessGuard is not None:
                 self.cgen.beginIf(lenAccessGuard)
             self.cgen.beginFor("uint32_t i = 0", "i < %s" % lenAccess, "++i")
@@ -383,6 +384,7 @@ class VulkanCountingCodegen(VulkanTypeIterator):
         lenAccess = self.lenAccessor(vulkanType)
         lenAccessGuard = self.lenAccessorGuard(vulkanType)
 
+        if lenAccess is not None:
             if lenAccessGuard is not None:
                 self.cgen.beginIf(lenAccessGuard)
             finalLenExpr = "%s * %s" % (lenAccess, self.cgen.sizeofExpr(vulkanType))

src/gfxstream/codegen/scripts/cereal/deepcopy.py

@@ -155,6 +155,7 @@ class DeepcopyCodegen(VulkanTypeIterator):
         lenAccessLhs = self.lenAccessorLhs(vulkanType)
 
         self.cgen.stmt("%s = nullptr" % accessRhs)
+        if lenAccessLhs is not None:
             self.cgen.beginIf("%s && %s" % (accessLhs, lenAccessLhs))
 
             self.cgen.stmt( \

src/gfxstream/codegen/scripts/cereal/handlemap.py

@@ -108,6 +108,7 @@ class HandleMapCodegen(VulkanTypeIterator):
         accessLhs = self.exprAccessor(vulkanType)
         lenAccess = self.lenAccessor(vulkanType)
 
+        if lenAccess is not None:
             self.cgen.stmt("%s->mapHandles_%s(%s%s, %s)" % \
                 (self.handlemapVarName, vulkanType.typeName,
                  self.makeCastExpr(vulkanType.getForAddressAccess().getForNonConstAccess()),

src/gfxstream/codegen/scripts/cereal/marshaling.py

@@ -455,6 +455,7 @@ class VulkanMarshalingCodegen(VulkanTypeIterator):
         lenAccess = self.lenAccessor(vulkanType)
 
         if self.direction == "write":
+            if lenAccess is not None:
                 self.cgen.stmt("saveStringArray(%s, %s, %s)" % (self.streamVarName,
                                                                 access, lenAccess))
         else:
@@ -468,7 +469,10 @@ class VulkanMarshalingCodegen(VulkanTypeIterator):
     def onStaticArr(self, vulkanType):
         access = self.exprValueAccessor(vulkanType)
         lenAccess = self.lenAccessor(vulkanType)
+        if lenAccess is not None:
             finalLenExpr = "%s * %s" % (lenAccess, self.cgen.sizeofExpr(vulkanType))
+        else:
+            finalLenExpr = self.cgen.sizeofExpr(vulkanType)
         self.genStreamCall(vulkanType, access, finalLenExpr)
 
     # Old version VkEncoder may have some sType values conflict with VkDecoder

src/gfxstream/codegen/scripts/cereal/reservedmarshaling.py

@@ -548,6 +548,7 @@ class VulkanReservedMarshalingCodegen(VulkanTypeIterator):
         lenAccessGuard = self.lenAccessorGuard(vulkanType)
 
         if self.direction == "write":
+            if lenAccess is not None:
                 self.cgen.beginBlock()
 
                 self.cgen.stmt("uint32_t c = 0")
@@ -578,6 +579,7 @@ class VulkanReservedMarshalingCodegen(VulkanTypeIterator):
     def onStaticArr(self, vulkanType):
         access = self.exprValueAccessor(vulkanType)
         lenAccess = self.lenAccessor(vulkanType)
+        if lenAccess is not None:
             finalLenExpr = "%s * %s" % (lenAccess, self.cgen.sizeofExpr(vulkanType))
             self.genStreamCall(vulkanType, access, finalLenExpr)
 

src/gfxstream/codegen/scripts/cereal/testing.py

@@ -205,6 +205,7 @@ class VulkanEqualityCodegen(VulkanTypeIterator):
             vulkanType,
             "Mismatch in string array pointer nullness")
 
+        if lenAccessLhs is not None and lenAccessRhs is not None:
             equalLenExpr = self.makeEqualExpr(lenAccessLhs, lenAccessRhs)
 
             self.compareWithConsequence( \
@@ -246,6 +247,7 @@ class VulkanEqualityCodegen(VulkanTypeIterator):
 
         lenAccessLhs = self.lenAccessorLhs(vulkanType)
 
+        if lenAccessLhs is not None:
             finalLenExpr = "%s * %s" % (lenAccessLhs,
                                         self.cgen.sizeofExpr(vulkanType))