[lld][WebAssembly] Error on import/export of mutable global without `mutable-globals...

Also add the +mutable-globals features in clang when
building with `-fPIC` since the linker will generate mutable
globals imports and exports in that case.

Differential Revision: https://reviews.llvm.org/D87537

diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index 1016873..d953082 100644 (file)
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -243,6 +243,27 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
     CC1Args.push_back("+sign-ext");
   }
 
+  if (!DriverArgs.hasFlag(options::OPT_mmutable_globals,
+                          options::OPT_mno_mutable_globals, false)) {
+    // -fPIC implies +mutable-globals because the PIC ABI used by the linker
+    // depends on importing and exporting mutable globals.
+    llvm::Reloc::Model RelocationModel;
+    unsigned PICLevel;
+    bool IsPIE;
+    std::tie(RelocationModel, PICLevel, IsPIE) =
+        ParsePICArgs(*this, DriverArgs);
+    if (RelocationModel == llvm::Reloc::PIC_) {
+      if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,
+                             options::OPT_mmutable_globals, false)) {
+        getDriver().Diag(diag::err_drv_argument_not_allowed_with)
+            << "-fPIC"
+            << "-mno-mutable-globals";
+      }
+      CC1Args.push_back("-target-feature");
+      CC1Args.push_back("+mutable-globals");
+    }
+  }
+
   if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {
     // '-fwasm-exceptions' is not compatible with '-mno-exception-handling'
     if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,

diff --git a/clang/test/Driver/wasm-toolchain.c b/clang/test/Driver/wasm-toolchain.c
index ad8b000..3c2eb66 100644 (file)
--- a/clang/test/Driver/wasm-toolchain.c
+++ b/clang/test/Driver/wasm-toolchain.c
@@ -119,3 +119,14 @@
 // RUN:   | FileCheck -check-prefix=CHECK-REACTOR %s
 // CHECK-REACTOR: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // CHECK-REACTOR: wasm-ld{{.*}}" "crt1-reactor.o" "--entry" "_initialize" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
+
+// -fPIC implies +mutable-globals
+
+// RUN: %clang %s -### -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=%s/no-sysroot-there -fPIC 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-PIC %s
+// CHECK-PIC: clang{{.*}}" "-cc1" {{.*}} "-target-feature" "+mutable-globals"
+
+// '-mno-mutable-globals' is not allowed with '-fPIC'
+// RUN: %clang %s -### -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=%s/no-sysroot-there -fPIC -mno-mutable-globals %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=PIC_NO_MUTABLE_GLOBALS %s
+// PIC_NO_MUTABLE_GLOBALS: error: invalid argument '-fPIC' not allowed with '-mno-mutable-globals'

diff --git a/lld/test/wasm/Inputs/undefined-globals.s b/lld/test/wasm/Inputs/undefined-globals.s
index 607d794..54dc418 100644 (file)
--- a/lld/test/wasm/Inputs/undefined-globals.s
+++ b/lld/test/wasm/Inputs/undefined-globals.s
@@ -7,5 +7,5 @@ use_undef_global:
   global.get used_undef_global
   end_function
 
-.globaltype unused_undef_global, i64
-.globaltype used_undef_global, i64
+.globaltype unused_undef_global, i64, immutable
+.globaltype used_undef_global, i64, immutable

diff --git a/lld/test/wasm/emit-relocs-fpic.s b/lld/test/wasm/emit-relocs-fpic.s
index c70e1e6..1d81ca6 100644 (file)
--- a/lld/test/wasm/emit-relocs-fpic.s
+++ b/lld/test/wasm/emit-relocs-fpic.s
@@ -1,6 +1,6 @@
-# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj -o %t.o < %s
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %s -o %t.o
 # RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown %p/Inputs/ret32.s -o %t.ret32.o
-# RUN: wasm-ld -pie --export-all --no-gc-sections --no-entry --emit-relocs -o %t.wasm %t.o %t.ret32.o
+# RUN: wasm-ld -pie --export-all --no-check-features --no-gc-sections --no-entry --emit-relocs -o %t.wasm %t.o %t.ret32.o
 # RUN: obj2yaml %t.wasm | FileCheck %s
 
 load_hidden_data:

diff --git a/lld/test/wasm/gc-imports.s b/lld/test/wasm/gc-imports.s
index 6564b5c..1f8bca9 100644 (file)
--- a/lld/test/wasm/gc-imports.s
+++ b/lld/test/wasm/gc-imports.s
@@ -31,7 +31,7 @@ _start:
 # CHECK-NEXT:         Field:           used_undef_global
 # CHECK-NEXT:         Kind:            GLOBAL
 # CHECK-NEXT:         GlobalType:      I64
-# CHECK-NEXT:         GlobalMutable:   true
+# CHECK-NEXT:         GlobalMutable:   false
 # CHECK-NEXT:   - Type:
 # CHECK:        - Type:            CUSTOM
 # CHECK-NEXT:     Name:            name
@@ -62,12 +62,12 @@ _start:
 # NO-GC-NEXT:         Field:           unused_undef_global
 # NO-GC-NEXT:         Kind:            GLOBAL
 # NO-GC-NEXT:         GlobalType:      I64
-# NO-GC-NEXT:         GlobalMutable:   true
+# NO-GC-NEXT:         GlobalMutable:   false
 # NO-GC-NEXT:       - Module:          env
 # NO-GC-NEXT:         Field:           used_undef_global
 # NO-GC-NEXT:         Kind:            GLOBAL
 # NO-GC-NEXT:         GlobalType:      I64
-# NO-GC-NEXT:         GlobalMutable:   true
+# NO-GC-NEXT:         GlobalMutable:   false
 # NO-GC-NEXT:   - Type:
 # NO-GC:        - Type:            CUSTOM
 # NO-GC-NEXT:     Name:            name

diff --git a/lld/test/wasm/mutable-globals.s b/lld/test/wasm/mutable-globals.s
new file mode 100644 (file)
index 0000000..98f216e
--- /dev/null
+++ b/lld/test/wasm/mutable-globals.s
@@ -0,0 +1,13 @@
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
+# RUN: not wasm-ld %t.o -o %t.wasm 2>&1 | FileCheck %s
+
+.globl _start
+_start:
+  .functype _start () -> ()
+  i32.const 1
+  global.set foo
+  end_function
+
+.globaltype foo, i32
+
+# CHECK: error: mutable global imported but 'mutable-globals' feature not present in inputs: `foo`. Use --no-check-features to suppress.

diff --git a/lld/test/wasm/pie.ll b/lld/test/wasm/pie.ll
index c576e7c..a203d31 100644 (file)
--- a/lld/test/wasm/pie.ll
+++ b/lld/test/wasm/pie.ll
@@ -1,4 +1,4 @@
-; RUN: llc -relocation-model=pic -filetype=obj %s -o %t.o
+; RUN: llc -relocation-model=pic -mattr=+mutable-globals -filetype=obj %s -o %t.o
 ; RUN: wasm-ld --no-gc-sections --allow-undefined -pie -o %t.wasm %t.o
 ; RUN: obj2yaml %t.wasm | FileCheck %s
 

diff --git a/lld/test/wasm/shared.ll b/lld/test/wasm/shared.ll
index 89fae33..59c1855 100644 (file)
--- a/lld/test/wasm/shared.ll
+++ b/lld/test/wasm/shared.ll
@@ -1,4 +1,4 @@
-; RUN: llc -relocation-model=pic -filetype=obj %s -o %t.o
+; RUN: llc -relocation-model=pic -mattr=+mutable-globals -filetype=obj %s -o %t.o
 ; RUN: wasm-ld -shared -o %t.wasm %t.o
 ; RUN: obj2yaml %t.wasm | FileCheck %s
 

diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index 495050c..fb4b79c 100644 (file)
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -461,6 +461,29 @@ void Writer::populateTargetFeatures() {
   if (!config->checkFeatures)
     return;
 
+  if (!config->relocatable && used.count("mutable-globals") == 0) {
+    for (Symbol *sym : symtab->getSymbols()) {
+      if (auto *global = dyn_cast<GlobalSymbol>(sym)) {
+        if (global->getGlobalType()->Mutable) {
+          if (!sym->isLive())
+            continue;
+          if (!sym->isUsedInRegularObj)
+            continue;
+          if (sym->isUndefined() && sym->isWeak() && !config->relocatable)
+            continue;
+          if (sym->isUndefined())
+            error(Twine("mutable global imported but 'mutable-globals' feature "
+                        "not present in inputs: `") +
+                  toString(*sym) + "`. Use --no-check-features to suppress.");
+          else if (sym->isExported())
+            error(Twine("mutable global exported but 'mutable-globals' feature "
+                        "not present in inputs: `") +
+                  toString(*sym) + "`. Use --no-check-features to suppress.");
+        }
+      }
+    }
+  }
+
   if (config->sharedMemory) {
     if (disallowed.count("shared-mem"))
       error("--shared-memory is disallowed by " + disallowed["shared-mem"] +