Merging r323485:

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r323485 | aemerson | 2018-01-26 01:27:22 +0100 (Fri, 26 Jan 2018) | 3 lines

[Driver] Add an -fexperimental-isel driver option to enable/disable GlobalISel.

Differential Revision: https://reviews.llvm.org/D42276
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_60@323745 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 31 insertions, 0 deletions

diff --git a/lib/Driver/ToolChains/Clang.cpp b/lib/Driver/ToolChains/Clang.cpp
index c445669a5a..484df52001 100644
--- a/lib/Driver/ToolChains/Clang.cpp
+++ b/lib/Driver/ToolChains/Clang.cpp
@@ -4639,6 +4639,37 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-fwhole-program-vtables");
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_fexperimental_isel,
+                               options::OPT_fno_experimental_isel)) {
+    CmdArgs.push_back("-mllvm");
+    if (A->getOption().matches(options::OPT_fexperimental_isel)) {
+      CmdArgs.push_back("-global-isel=1");
+
+      // GISel is on by default on AArch64 -O0, so don't bother adding
+      // the fallback remarks for it. Other combinations will add a warning of
+      // some kind.
+      bool IsArchSupported = Triple.getArch() == llvm::Triple::aarch64;
+      bool IsOptLevelSupported = false;
+
+      Arg *A = Args.getLastArg(options::OPT_O_Group);
+      if (Triple.getArch() == llvm::Triple::aarch64) {
+        if (!A || A->getOption().matches(options::OPT_O0))
+          IsOptLevelSupported = true;
+      }
+      if (!IsArchSupported || !IsOptLevelSupported) {
+        CmdArgs.push_back("-mllvm");
+        CmdArgs.push_back("-global-isel-abort=2");
+
+        if (!IsArchSupported)
+          D.Diag(diag::warn_drv_experimental_isel_incomplete) << Triple.getArchName();
+        else
+          D.Diag(diag::warn_drv_experimental_isel_incomplete_opt);
+      }
+    } else {
+      CmdArgs.push_back("-global-isel=0");
+    }
+  }
+
   // Finally add the compile command to the compilation.
   if (Args.hasArg(options::OPT__SLASH_fallback) &&
       Output.getType() == types::TY_Object &&