compiler: revert `for package-scope "a = b; b = x" just set "a = x"`
This patch to the Go frontend reverts https://go.dev/cl/245098, which
introduced incorrect initialization ordering. This patch adjusts the
runtime package to work even with that change reverted.
Original description of change 245098:
This avoids requiring an init function to initialize the variable.
This can only be done if x is a static initializer.
The go1.15rc1 runtime package relies on this optimization.
The package has a variable "var maxSearchAddr = maxOffAddr".
The maxSearchAddr variable is used by code that runs before package
initialization is complete.
This is for https://golang.org/issue/51913.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu. Committed
to mainline.
Ian
5d6db440fd8ec4089fba83760874d70f449037a6
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 75ee2e3aaca..bcb526c85b9 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-323ab0e6fab89978bdbd83dca9c2ad9c5dcd690f
+62fc90f52da2f52cbe3b4f10e560dc6aa59baeb5
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/gogo.cc b/gcc/go/gofrontend/gogo.cc
index 30d5c9fcb0b..d35c6baf582 100644
--- a/gcc/go/gofrontend/gogo.cc
+++ b/gcc/go/gofrontend/gogo.cc
@@ -1612,31 +1612,16 @@ Gogo::write_globals()
// The initializer is constant if it is the zero-value of the
// variable's type or if the initial value is an immutable value
// that is not copied to the heap.
- Expression* init = var->init();
-
- // If we see "a = b; b = x", and x is a static
- // initializer, just set a to x.
- while (init != NULL && init->var_expression() != NULL)
- {
- Named_object* ino = init->var_expression()->named_object();
- if (!ino->is_variable() || ino->package() != NULL)
- break;
- Expression* ino_init = ino->var_value()->init();
- if (ino->var_value()->has_pre_init()
- || ino_init == NULL
- || !ino_init->is_static_initializer())
- break;
- init = ino_init;
- }
-
- bool is_static_initializer;
- if (init == NULL)
+ bool is_static_initializer = false;
+ if (var->init() == NULL)
is_static_initializer = true;
else
{
Type* var_type = var->type();
- init = Expression::make_cast(var_type, init,
var->location());
- is_static_initializer = init->is_static_initializer();
+ Expression* init = var->init();
+ Expression* init_cast =
+ Expression::make_cast(var_type, init, var->location());
+ is_static_initializer = init_cast->is_static_initializer();
}
// Non-constant variable initializations might need to create
@@ -1655,15 +1640,7 @@ Gogo::write_globals()
}
var_init_fn = init_fndecl;
}
-
- Bexpression* var_binit;
- if (init == NULL)
- var_binit = NULL;
- else
- {
- Translate_context context(this, var_init_fn, NULL, NULL);
- var_binit = init->get_backend(&context);
- }
+ Bexpression* var_binit = var->get_init(this, var_init_fn);
if (var_binit == NULL)
;
diff --git a/libgo/go/runtime/mpagealloc.go b/libgo/go/runtime/mpagealloc.go
index 2725e3b7c7b..5e40da45d17 100644
--- a/libgo/go/runtime/mpagealloc.go
+++ b/libgo/go/runtime/mpagealloc.go
@@ -87,7 +87,9 @@ const (
//
// We alias maxOffAddr just to make it clear that this is the maximum address
// for the page allocator's search space. See maxOffAddr for details.
-var maxSearchAddr = maxOffAddr
+func maxSearchAddr() offAddr {
+ return maxOffAddr
+}
// Global chunk index.
//
@@ -331,13 +333,13 @@ func (p *pageAlloc) init(mheapLock *mutex, sysStat
*sysMemStat) {
p.sysInit()
// Start with the searchAddr in a state indicating there's no free
memory.
- p.searchAddr = maxSearchAddr
+ p.searchAddr = maxSearchAddr()
// Set the mheapLock.
p.mheapLock = mheapLock
// Initialize scavenge tracking state.
- p.scav.scavLWM = maxSearchAddr
+ p.scav.scavLWM = maxSearchAddr()
}
// tryChunkOf returns the bitmap data for the given chunk.
@@ -760,7 +762,7 @@ nextLevel:
}
if l == 0 {
// We're at level zero, so that means we've exhausted
our search.
- return 0, maxSearchAddr
+ return 0, maxSearchAddr()
}
// We're not at level zero, and we exhausted the level we were
looking in.
@@ -854,7 +856,7 @@ func (p *pageAlloc) alloc(npages uintptr) (addr uintptr,
scav uintptr) {
// exhausted. Otherwise, the heap still might have free
// space in it, just not enough contiguous space to
// accommodate npages.
- p.searchAddr = maxSearchAddr
+ p.searchAddr = maxSearchAddr()
}
return 0, 0
}
diff --git a/libgo/go/runtime/mpagecache.go b/libgo/go/runtime/mpagecache.go
index 7206e2dbdb7..5bad4f789a1 100644
--- a/libgo/go/runtime/mpagecache.go
+++ b/libgo/go/runtime/mpagecache.go
@@ -143,7 +143,7 @@ func (p *pageAlloc) allocToCache() pageCache {
if addr == 0 {
// We failed to find adequate free space, so mark the
searchAddr as OoM
// and return an empty pageCache.
- p.searchAddr = maxSearchAddr
+ p.searchAddr = maxSearchAddr()
return pageCache{}
}
ci := chunkIndex(addr)
