[PATCH] D40127: [Driver][ARM] For assembler files recognize -Xassembler or -Wa, -mthumb

[Peter Smith via Phabricator via cfe-commits]

peter.smith created this revision.
Herald added subscribers: kristof.beyls, javed.absar, aemerson.

The Unified Arm Assembler Language is designed so that the majority of assembler files can be assembled for both Arm and Thumb with the choice made as a compilation option. The way this is done in gcc is to pass -mthumb to the assembler with either -Wa,-mthumb or -Xassembler -mthumb. This change adds support for these options to clang. There is no assembler equivalent of -mno-thumb, -marm or -mno-arm so we don't need to recognize these.

      

Ideally we would do all of the processing in CollectArgsForIntegratedAssembler(). Unfortunately we need to change the triple and at that point it is too late. Instead we look for the option earlier in ComputeLLVMTriple().

      

Fixes PR34519


https://reviews.llvm.org/D40127

Files:
  lib/Driver/ToolChain.cpp
  lib/Driver/ToolChains/Clang.cpp
  test/Driver/arm-target-as-mthumb.s


Index: test/Driver/arm-target-as-mthumb.s
===================================================================
--- /dev/null
+++ test/Driver/arm-target-as-mthumb.s
@@ -0,0 +1,17 @@
+// Make sure -mthumb does not affect assembler triple, but -Wa,-mthumb or
+// -Xassembler -mthumb does. Also check that -Wa,-mthumb or -Xassembler -mthumb
+// does not affect non assembler files.
+
+// RUN: %clang -target armv7a-linux-gnueabi -### -c -mthumb %s 2>&1 | \
+// RUN: FileCheck -check-prefix=TRIPLE-ARM %s
+// RUN: %clang -target armv7a-linux-gnueabi -### -c -Wa,-mthumb \
+// RUN: %S/Inputs/wildcard1.c  2>&1 | FileCheck -check-prefix=TRIPLE-ARM %s
+
+// TRIPLE-ARM: "-triple" "armv7--linux-gnueabi"
+
+// RUN: %clang -target armv7a-linux-gnueabi -### -c -Wa,-mthumb %s 2>&1 | \
+// RUN: FileCheck -check-prefix=TRIPLE-THUMB %s
+// RUN: %clang -target armv7a-linux-gnueabi -### -c -Xassembler -mthumb %s \
+// RUN: 2>&1 | FileCheck -check-prefix=TRIPLE-THUMB %s
+
+// TRIPLE-THUMB: "-triple" "thumbv7--linux-gnueabi"
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -1889,6 +1889,15 @@
       switch (C.getDefaultToolChain().getArch()) {
       default:
         break;
+      case llvm::Triple::thumb:
+      case llvm::Triple::thumbeb:
+      case llvm::Triple::arm:
+      case llvm::Triple::armeb:
+        if (Value == "-mthumb")
+          // -mthumb has already been processed in ComputeLLVMTriple()
+          // recognize but skip over here.
+          continue;
+
       case llvm::Triple::mips:
       case llvm::Triple::mipsel:
       case llvm::Triple::mips64:
Index: lib/Driver/ToolChain.cpp
===================================================================
--- lib/Driver/ToolChain.cpp
+++ lib/Driver/ToolChain.cpp
@@ -541,11 +541,27 @@
           << tools::arm::getARMArch(MArch, getTriple()) << "ARM";
     }
 
-    // Assembly files should start in ARM mode, unless arch is M-profile.
-    // Windows is always thumb.
-    if ((InputType != types::TY_PP_Asm && Args.hasFlag(options::OPT_mthumb,
-         options::OPT_mno_thumb, ThumbDefault)) || IsMProfile ||
-         getTriple().isOSWindows()) {
+    // Check for -mthumb passed explicitly to the assembler via -Wa or
+    // -Xassembler. Ideally we would do this in
+    // CollectArgsForIntegratedAssembler but we can't change the ArchName at
+    // that point. There is no assembler equivalent of -mno-thumb, -marm, or
+    // -mno-arm.
+    bool IsIntegratedAssemblerThumb = false;
+    for (const Arg *A :
+         Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
+      for (StringRef Value : A->getValues()) {
+        if (Value == "-mthumb")
+          IsIntegratedAssemblerThumb = true;
+      }
+    }
+    // Assembly files should start in ARM mode, unless arch is M-profile, or
+    // -mthumb has been passed explicitly to the assembler. Windows is always
+    // thumb.
+    if ((InputType != types::TY_PP_Asm &&
+         Args.hasFlag(options::OPT_mthumb, options::OPT_mno_thumb,
+                      ThumbDefault)) ||
+        (InputType == types::TY_PP_Asm && IsIntegratedAssemblerThumb) ||
+        IsMProfile || getTriple().isOSWindows()) {
       if (IsBigEndian)
         ArchName = "thumbeb";
       else


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