From fc7f3b7514147cb6fc0ea67a5b0ee61e59d1ef6e Mon Sep 17 00:00:00 2001
From: NAKAMURA Takumi <geek4civic@gmail.com>
Date: Sat, 17 Jun 2017 03:19:08 +0000
Subject: [CMake] Introduce LLVM_TARGET_TRIPLE_ENV as an option to override
 LLVM_DEFAULT_TARGET_TRIPLE at runtime.

No behavior is changed if LLVM_TARGET_TRIPLE_ENV is blank or undefined.

If LLVM_TARGET_TRIPLE_ENV is "TEST_TARGET_TRIPLE" and $TEST_TARGET_TRIPLE is not blank,
llvm::sys::getDefaultTargetTriple() returns $TEST_TARGET_TRIPLE.
Lit resets config.target_triple and config.environment[LLVM_TARGET_TRIPLE_ENV] to change the default target.

Without changing LLVM_DEFAULT_TARGET_TRIPLE nor rebuilding, lit can be run;

  TEST_TARGET_TRIPLE=i686-pc-win32 bin/llvm-lit -sv path/to/test/
  TEST_TARGET_TRIPLE=i686-pc-win32 ninja check-clang-tools

Differential Revision: https://reviews.llvm.org/D33662

llvm-svn: 305632
---
 llvm/lib/Support/Unix/Host.inc | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'llvm/lib/Support/Unix')

diff --git a/llvm/lib/Support/Unix/Host.inc b/llvm/lib/Support/Unix/Host.inc
index 457217125a2..0ba6a25aa19 100644
--- a/llvm/lib/Support/Unix/Host.inc
+++ b/llvm/lib/Support/Unix/Host.inc
@@ -45,5 +45,11 @@ std::string sys::getDefaultTargetTriple() {
     TargetTripleString += getOSVersion();
   }
 
+  // Override the default target with an environment variable named by LLVM_TARGET_TRIPLE_ENV.
+#if defined(LLVM_TARGET_TRIPLE_ENV)
+  if (const char *EnvTriple = std::getenv(LLVM_TARGET_TRIPLE_ENV))
+    TargetTripleString = EnvTriple;
+#endif
+
   return Triple::normalize(TargetTripleString);
 }
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