[driver][mips] Adjust target triple accordingly to provided ABI name

[atanasyan]

Summary

Explicitly selected MIPS ABI using the -mabi option implies corresponding target triple. For 'O32' ABI it's a 32-bit target triple like mips-linux-gnu. For 'N32' and 'N64' ABIs it's a 64-bit target triple like mips64-linux-gnu. This patch adjusts target triple accordingly these rules like we do for pseudo-target flags '-m64', '-m32' etc already.

[atanasyan]

Ping?

[rnk]

Should --target=mipsZZZ -mabi=n64 be meaningful? What does clang --target=i686-linux-gnu -m64 do? If this matches that, then let's do it.

I think each listed reviewer is currently at CppCon, hence the delay.

[atanasyan]

In D52290#1245222, @rnk wrote:

Should --target=mipsZZZ -mabi=n64 be meaningful? What does clang --target=i686-linux-gnu -m64 do? If this matches that, then let's do it.

Thanks. Initially I thought that providing different target triple and -mabi option explicitly is an error. But now I see that it's better and consistent with other targets to adjust a target triple accordingly to -mabi options in any (implicit/explicit) case. I will update the patch soon.

[atanasyan]

Always adjust target triple (explicitly and implicitly provided) accordingly to ABI name.

[rnk]

lib/Driver/Driver.cpp

492

We should emit a diagnostic for invalid -mabi=values.

[atanasyan]

lib/Driver/Driver.cpp

492

We already do that:

$ clang -target mips-linux-gnu -c test.c -mabi=xxx
error: unknown target ABI 'xxx'

[rnk]

Lgtm, thanks!

[atanasyan]

Thanks for review.

[MaskRay]

cfe/trunk/lib/Driver/Driver.cpp

486 ↗

(On Diff #167237)

getLastArg claims the option for non-mips architecture and makes other architectures silently accept unknown -mabi=. This was fixed by D134671.

lib/Driver/Driver.cpp

if (Args.hasFlag(options::OPT_miamcu, options::OPT_mno_iamcu, false)) {
     Target.setArchName("i586");
     Target.setEnvironment(llvm::Triple::UnknownEnvironment);
     Target.setEnvironmentName("");
     Target.setOS(llvm::Triple::ELFIAMCU);
     Target.setVendor(llvm::Triple::UnknownVendor);
     Target.setVendorName("intel");
   }
 
+  // If target is MIPS and there is no explicit `-target` option,
+  // adjust the target triple accordingly to provided ABI name.
+  if (Target.isMIPS() && !Args.getLastArg(options::OPT_target)) {
+    if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
+      Target = llvm::StringSwitch<llvm::Triple>(A->getValue())
+                   .Case("32", Target.get32BitArchVariant())
+                   .Case("n32", Target.get64BitArchVariant())
+                   .Case("64", Target.get64BitArchVariant())
+                   .Default(Target);
+  }
+
   return Target;
 }
 
 // Parse the LTO options and record the type of LTO compilation
 // based on which -f(no-)?lto(=.*)? option occurs last.
 void Driver::setLTOMode(const llvm::opt::ArgList &Args) {
   LTOMode = LTOK_None;
   if (!Args.hasFlag(options::OPT_flto, options::OPT_flto_EQ,

test/Driver/mips-target-abi.c

+// Check default target triple adjusting by ABI option.
+//
+// REQUIRES: mips-default-target
+//
+// RUN: %clang -mabi=32 -### %s 2>&1 | FileCheck -check-prefix=O32 %s
+// O32: "-triple" "mips{{[^"]*}}"
+// O32: "-target-cpu" "mips32r2"
+// O32: "-target-abi" "o32"
+// O32: ld{{.*}}"
+// O32: "-m" "elf32btsmip"
+
+// RUN: %clang -mabi=n32 -### %s 2>&1 | FileCheck -check-prefix=N32 %s
+// N32: "-triple" "mips64{{[^"]*}}"
+// N32: "-target-cpu" "mips64r2"
+// N32: "-target-abi" "n32"
+// N32: ld{{.*}}"
+// N32: "-m" "elf32btsmipn32"
+
+// RUN: %clang -mabi=64 -### %s 2>&1 | FileCheck -check-prefix=N64 %s
+// N64: "-triple" "mips64{{[^"]*}}"
+// N64: "-target-cpu" "mips64r2"
+// N64: "-target-abi" "n64"
+// N64: ld{{.*}}"
+// N64: "-m" "elf64btsmip"

test/lit.cfg.py

 
 if is_filesystem_case_insensitive():
     config.available_features.add('case-insensitive-filesystem')
 
 # Tests that require the /dev/fd filesystem.
 if os.path.exists('/dev/fd/0') and sys.platform not in ['cygwin']:
     config.available_features.add('dev-fd-fs')
 
+# Test that default target triple is mips*
+if re.match(r'^mips*', config.target_triple):
+    config.available_features.add('mips-default-target')
+
 # Not set on native MS environment.
 if not re.match(r'.*-(windows-msvc)$', config.target_triple):
     config.available_features.add('non-ms-sdk')
 
 # Not set on native PS4 environment.
 if not re.match(r'.*-scei-ps4', config.target_triple):
     config.available_features.add('non-ps4-sdk')