[lldb] Remove the global platform list

This patch moves the platform creation and selection logic into the
per-debugger platform lists. I've tried to keep functional changes to a
minimum -- the main (only) observable difference in this change is that
APIs, which select a platform by name (e.g.,
Debugger::SetCurrentPlatform) will not automatically pick up a platform
associated with another debugger (or no debugger at all).

I've also added several tests for this functionality -- one of the
pleasant consequences of the debugger isolation is that it is now
possible to test the platform selection and creation logic.

This is a product of the discussion at
<https://discourse.llvm.org/t/multiple-platforms-with-the-same-name/59594>.

Differential Revision: https://reviews.llvm.org/D120810

lldb/test/API/python_api/debugger/TestDebuggerAPI.py

@@ -92,3 +92,55 @@ class DebuggerAPITestCase(TestBase):
 
         # Test the local property again, is it set to new_cache_line_size?
         self.assertEqual(get_cache_line_size(), new_cache_line_size)
+
+    def test_CreateTarget_platform(self):
+        exe = self.getBuildArtifact("a.out")
+        self.yaml2obj("elf.yaml", exe)
+        error = lldb.SBError()
+        target1 = self.dbg.CreateTarget(exe, None, "remote-linux",
+                False, error)
+        self.assertSuccess(error)
+        platform1 = target1.GetPlatform()
+        platform1.SetWorkingDirectory("/foo/bar")
+
+        # Reuse a platform if it matches the currently selected one...
+        target2 = self.dbg.CreateTarget(exe, None, "remote-linux",
+                False, error)
+        self.assertSuccess(error)
+        platform2 = target2.GetPlatform()
+        self.assertEqual(platform2.GetWorkingDirectory(), "/foo/bar")
+
+        # ... but create a new one if it doesn't.
+        self.dbg.SetSelectedPlatform(lldb.SBPlatform("remote-windows"))
+        target3 = self.dbg.CreateTarget(exe, None, "remote-linux",
+                False, error)
+        self.assertSuccess(error)
+        platform3 = target3.GetPlatform()
+        self.assertIsNone(platform3.GetWorkingDirectory())
+
+    def test_CreateTarget_arch(self):
+        exe = self.getBuildArtifact("a.out")
+        if lldbplatformutil.getHostPlatform() == 'linux':
+            self.yaml2obj("macho.yaml", exe)
+            arch = "x86_64-apple-macosx"
+        else:
+            self.yaml2obj("elf.yaml", exe)
+            arch = "x86_64-pc-linux"
+
+        fbsd = lldb.SBPlatform("remote-freebsd")
+        self.dbg.SetSelectedPlatform(fbsd)
+
+        error = lldb.SBError()
+        target1 = self.dbg.CreateTarget(exe, arch, None, False, error)
+        self.assertSuccess(error)
+        platform1 = target1.GetPlatform()
+        self.assertEqual(platform1.GetName(), "remote-macosx")
+        platform1.SetWorkingDirectory("/foo/bar")
+
+        # Reuse a platform even if it is not currently selected.
+        self.dbg.SetSelectedPlatform(fbsd)
+        target2 = self.dbg.CreateTarget(exe, arch, None, False, error)
+        self.assertSuccess(error)
+        platform2 = target2.GetPlatform()
+        self.assertEqual(platform2.GetName(), "remote-macosx")
+        self.assertEqual(platform2.GetWorkingDirectory(), "/foo/bar")

lldb/test/API/python_api/debugger/elf.yaml

@@ -0,0 +1,35 @@
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x4
+    Content:         "c3c3c3c3"
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC ]
+    Address:         0x2000
+    AddressAlign:    0x4
+    Content:         "3232"
+ProgramHeaders:
+  - Type: PT_LOAD
+    Flags: [ PF_X, PF_R ]
+    VAddr: 0x1000
+    PAddr: 0x1000
+    Align: 0x4
+    FirstSec: .text
+    LastSec:  .text
+  - Type: PT_LOAD
+    Flags: [ PF_R, PF_W ]
+    VAddr: 0x2000
+    PAddr: 0x1004
+    Align: 0x4
+    FirstSec: .data
+    LastSec:  .data
+

lldb/test/API/python_api/debugger/macho.yaml

@@ -0,0 +1,42 @@
+--- !mach-o
+FileHeader:      
+  magic:           0xFEEDFACF
+  cputype:         0x01000007
+  cpusubtype:      0x00000003
+  filetype:        0x00000001
+  ncmds:           4
+  sizeofcmds:      1160
+  flags:           0x00002000
+  reserved:        0x00000000
+LoadCommands:    
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         1032
+    segname:         ''
+    vmaddr:          0
+    vmsize:          744
+    fileoff:         1192
+    filesize:        744
+    maxprot:         7
+    initprot:        7
+    nsects:          12
+    flags:           0
+    Sections:        
+      - sectname:        __text
+        segname:         __TEXT
+        addr:            0x0000000000000000
+        size:            22
+        offset:          0x000004A8
+        align:           4
+        reloff:          0x00000000
+        nreloc:          0
+        flags:           0x80000400
+        reserved1:       0x00000000
+        reserved2:       0x00000000
+        reserved3:       0x00000000
+  - cmd:             LC_BUILD_VERSION
+    cmdsize:         24
+    platform:        1
+    minos:           658944
+    sdk:             658944
+    ntools:          0
+...

lldb/test/API/python_api/sbplatform/TestSBPlatform.py

@@ -25,6 +25,29 @@ class SBPlatformAPICase(TestBase):
         plat = lldb.SBPlatform("remote-linux") # arbitrary choice
         self.assertTrue(plat)
         plat.SetSDKRoot(self.getBuildDir())
-        self.dbg.SetCurrentPlatform("remote-linux")
+        self.dbg.SetSelectedPlatform(plat)
         self.expect("platform status",
                 substrs=["Sysroot:", self.getBuildDir()])
+
+    def test_SetCurrentPlatform_floating(self):
+        # floating platforms cannot be referenced by name until they are
+        # associated with a debugger
+        floating_platform = lldb.SBPlatform("remote-netbsd")
+        floating_platform.SetWorkingDirectory(self.getBuildDir())
+        self.assertSuccess(self.dbg.SetCurrentPlatform("remote-netbsd"))
+        dbg_platform = self.dbg.GetSelectedPlatform()
+        self.assertEqual(dbg_platform.GetName(), "remote-netbsd")
+        self.assertIsNone(dbg_platform.GetWorkingDirectory())
+
+    def test_SetCurrentPlatform_associated(self):
+        # associated platforms are found by name-based lookup
+        floating_platform = lldb.SBPlatform("remote-netbsd")
+        floating_platform.SetWorkingDirectory(self.getBuildDir())
+        orig_platform = self.dbg.GetSelectedPlatform()
+
+        self.dbg.SetSelectedPlatform(floating_platform)
+        self.dbg.SetSelectedPlatform(orig_platform)
+        self.assertSuccess(self.dbg.SetCurrentPlatform("remote-netbsd"))
+        dbg_platform = self.dbg.GetSelectedPlatform()
+        self.assertEqual(dbg_platform.GetName(), "remote-netbsd")
+        self.assertEqual(dbg_platform.GetWorkingDirectory(), self.getBuildDir())