[PATCH] D124999: ld.lld: Respect -fallback-gnu-driver.

[Shea Levy via Phabricator via llvm-commits]

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This is essentially a run-time version of LLD_DEFAULT_LD_LLD_IS_MINGW.

-fallback-gnu-driver must be the first argument (after -flavor, if it exists).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D124999

Files:
  lld/test/MinGW/driver.test
  lld/tools/lld/lld.cpp


Index: lld/tools/lld/lld.cpp
===================================================================
--- lld/tools/lld/lld.cpp
+++ lld/tools/lld/lld.cpp
@@ -78,7 +78,33 @@
   return s == "i386pe" || s == "i386pep" || s == "thumb2pe" || s == "arm64pe";
 }
 
+enum GnuDriver { MinGWDriver, ELFDriver, InvalidDriver };
+
+static GnuDriver getDriver(StringRef s) {
+  return StringSwitch<GnuDriver>(s)
+      .CaseLower("elf", ELFDriver)
+      .CaseLower("mingw", MinGWDriver)
+      .Default(InvalidDriver);
+}
+
 static bool isPETarget(std::vector<const char *> &v) {
+  GnuDriver fallbackDriver =
+#ifdef LLD_DEFAULT_LD_LLD_IS_MINGW
+      MinGWDriver;
+#else
+      ELFDriver;
+#endif
+
+  // Parse -fallback-gnu-driver option.
+  if (v.size() > 1 && v[1] == StringRef("-fallback-gnu-driver")) {
+    if (v.size() <= 2)
+      die("missing arg value for '-fallback-gnu-driver'");
+    fallbackDriver = getDriver(v[2]);
+    if (fallbackDriver == InvalidDriver)
+      die("Unknown fallback gnu driver: " + StringRef(v[2]));
+    v.erase(v.begin() + 1, v.begin() + 3);
+  }
+
   for (auto it = v.begin(); it + 1 != v.end(); ++it) {
     if (StringRef(*it) != "-m")
       continue;
@@ -96,11 +122,7 @@
     return isPETargetName(*(it + 1));
   }
 
-#ifdef LLD_DEFAULT_LD_LLD_IS_MINGW
-  return true;
-#else
-  return false;
-#endif
+  return fallbackDriver == MinGWDriver;
 }
 
 static Flavor parseProgname(StringRef progname) {
Index: lld/test/MinGW/driver.test
===================================================================
--- lld/test/MinGW/driver.test
+++ lld/test/MinGW/driver.test
@@ -246,6 +246,7 @@
 VERSION: LLD {{.*}} (compatible with GNU linkers)
 
 RUN: ld.lld -m i386pep --help 2>&1 | FileCheck -check-prefix=HELP %s
+RUN: ld.lld -fallback-gnu-driver mingw --help 2>&1 | FileCheck -check-prefix=HELP %s
 HELP: USAGE:
 HELP: --enable-auto-import
 


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