[vm/infra] Fix compiler_configuration to use existing cross-compiler.

Also fix the ELF loader to allow segment alignment >page size.

Change-Id: Icc4c2eaae44171e74cc41d9f2b06701acad86a90
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/118983
Commit-Queue: Samir Jindel <[email protected]>
Reviewed-by: Alexander Thomas <[email protected]>

Author: sjindel-google

pkg/test_runner/lib/src/compiler_configuration.dart

@@ -590,8 +590,6 @@ class PrecompilerCompilerConfiguration extends CompilerConfiguration
 
   bool get _isArm64 => _configuration.architecture == Architecture.arm64;
 
-  bool get _isSimArm64 => _configuration.architecture == Architecture.simarm64;
-
   bool get _isX64 => _configuration.architecture == Architecture.x64;
 
   bool get _isIA32 => _configuration.architecture == Architecture.ia32;
@@ -705,12 +703,12 @@ class PrecompilerCompilerConfiguration extends CompilerConfiguration
   Command computeAssembleCommand(String tempDir, List arguments,
       Map<String, String> environmentOverrides) {
     String cc, shared, ldFlags;
-    if (_isAndroid || _isSimArm || _isSimArm64) {
+    if (_isAndroid) {
       var ndk = "third_party/android_tools/ndk";
       String triple;
-      if (_isArm || _isSimArm) {
+      if (_isArm) {
         triple = "arm-linux-androideabi";
-      } else if (_isArm64 || _isSimArm64) {
+      } else if (_isArm64) {
         triple = "aarch64-linux-android";
       }
       String host;
@@ -722,7 +720,11 @@ class PrecompilerCompilerConfiguration extends CompilerConfiguration
       cc = "$ndk/toolchains/$triple-4.9/prebuilt/$host-x86_64/bin/$triple-gcc";
       shared = '-shared';
     } else if (Platform.isLinux) {
-      cc = 'gcc';
+      if (_isSimArm) {
+        cc = 'arm-linux-gnueabihf-gcc';
+      } else {
+        cc = 'gcc';
+      }
       shared = '-shared';
     } else if (Platform.isMacOS) {
       cc = 'clang';

runtime/bin/elf_loader.cc

@@ -224,6 +224,7 @@ bool LoadedElf::ReadSectionStringTable() {
 bool LoadedElf::LoadSegments() {
   // Calculate the total amount of virtual memory needed.
   uword total_memory = 0;
+  uword maximum_alignment = PageSize();
   for (uword i = 0; i < header_.num_program_headers; ++i) {
     const dart::elf::ProgramHeader header = program_table_[i];
 
@@ -235,13 +236,12 @@ bool LoadedElf::LoadSegments() {
         total_memory);
     CHECK_ERROR(Utils::IsPowerOfTwo(header.alignment),
                 "Alignment must be a power of two.");
-    CHECK_ERROR(header.alignment <= PageSize(),
-                "Cannot align greater than page size.")
+    maximum_alignment = Utils::Maximum(maximum_alignment, header.alignment);
   }
   total_memory = Utils::RoundUp(total_memory, PageSize());
 
   base_.reset(VirtualMemory::AllocateAligned(
-      total_memory, /*alignment=*/PageSize(),
+      total_memory, /*alignment=*/maximum_alignment,
       /*is_executable=*/false, /*mapping name=*/filename_.get()));
   CHECK_ERROR(base_ != nullptr, "Could not reserve virtual memory.");