Make thumb the default instruction set for v7m and v7em

[bogden]

Summary

Depends on http://llvm-reviews.chandlerc.com/differential/diff/5255.

Fixes http://llvm.org/bugs/show_bug.cgi?id=17559

[bogden]

An alternative approach would be to enable thumb by default on all targets that support thumb2 - which would be more compatible with modern (hard-float) gccs.

But that's likely a bit more controversial than simply fixing the 7M targets, so I'll prepare a separate patch.

[rengolin]

committed in 197152

lib/Driver/ToolChain.cpp

case llvm::Triple::thumb: {
     // FIXME: Factor into subclasses.
     llvm::Triple Triple = getTriple();
 
     // Thumb2 is the default for V7 on Darwin.
     //
     // FIXME: Thumb should just be another -target-feaure, not in the triple.
     StringRef Suffix =
       getLLVMArchSuffixForARM(getARMTargetCPU(Args, Triple));
-    bool ThumbDefault = Suffix.startswith("v6m") ||
+    bool ThumbDefault = Suffix.startswith("v6m") || Suffix.startswith("v7m") ||
+      Suffix.startswith("v7em") ||
       (Suffix.startswith("v7") && getTriple().isOSDarwin());
     std::string ArchName = "arm";
 
     // Assembly files should start in ARM mode.
     if (InputType != types::TY_PP_Asm &&
         Args.hasFlag(options::OPT_mthumb, options::OPT_mno_thumb, ThumbDefault))
       ArchName = "thumb";
     Triple.setArchName(ArchName + Suffix.str());

test/Driver/arm-cortex-cpus.c

 // RUN: %clang -target armv6t2 -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V6T2-THUMB %s
 // RUN: %clang -target arm -march=armv6t2 -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V6T2-THUMB %s
 // CHECK-V6T2-THUMB: "-cc1"{{.*}} "-triple" "thumbv6t2-{{.*}} "-target-cpu" "arm1156t2-s"
 
 // RUN: %clang -target armv6m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V6M %s
 // RUN: %clang -target arm -march=armv6m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V6M %s
 // CHECK-V6M: "-cc1"{{.*}} "-triple" "thumbv6m-{{.*}} "-target-cpu" "cortex-m0"
 
-// RUN: %clang -target armv7m-apple-darwin -arch armv7m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7M %s
+// RUN: %clang -target armv7m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7M %s
+// RUN: %clang -target arm -march=armv7-m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7M %s
 // CHECK-V7M: "-cc1"{{.*}} "-triple" "thumbv7m-{{.*}} "-target-cpu" "cortex-m3"
 
-// RUN: %clang -target armv7em-apple-darwin -arch armv7em -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7EM %s
+// RUN: %clang -target armv7em -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7EM %s
+// RUN: %clang -target arm -march=armv7e-m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7EM %s
 // CHECK-V7EM: "-cc1"{{.*}} "-triple" "thumbv7em-{{.*}} "-target-cpu" "cortex-m4"
 
 // RUN: %clang -target armv6m-apple-darwin -arch armv6m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V6M-DARWIN %s
 // CHECK-V6M-DARWIN: "-cc1"{{.*}} "-triple" "thumbv6m-{{.*}} "-target-cpu" "cortex-m0"
 
 // RUN: %clang -target armv7m-apple-darwin -arch armv7m -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-V7M-DARWIN %s
 // CHECK-V7M-DARWIN: "-cc1"{{.*}} "-triple" "thumbv7m-{{.*}} "-target-cpu" "cortex-m3"
 

 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-a12 -mthumb  -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7A-THUMB %s
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-a15 -mthumb  -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7A-THUMB %s
 // CHECK-CPUV7A-THUMB: "-cc1"{{.*}} "-triple" "thumbv7-{{.*}}
 
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-m0 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV6M %s
 // CHECK-CPUV6M: "-cc1"{{.*}} "-triple" "thumbv6m-{{.*}}
 
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-m3 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7M %s
-// CHECK-CPUV7M: "-cc1"{{.*}} "-triple" "armv7m-{{.*}}
+// CHECK-CPUV7M: "-cc1"{{.*}} "-triple" "thumbv7m-{{.*}}
 
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-m4 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7EM %s
-// CHECK-CPUV7EM: "-cc1"{{.*}} "-triple" "armv7em-{{.*}}
+// CHECK-CPUV7EM: "-cc1"{{.*}} "-triple" "thumbv7em-{{.*}}
 
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-r4 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7R %s
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-r5 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7R %s
 // CHECK-CPUV7R: "-cc1"{{.*}} "-triple" "armv7r-{{.*}}
 
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-r4 -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7R-THUMB %s
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-r5 -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV7R-THUMB %s
 // CHECK-CPUV7R-THUMB: "-cc1"{{.*}} "-triple" "thumbv7r-{{.*}}
 
 // RUN: %clang -target arm -mcpu=cortex-a53 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV8A %s
 // RUN: %clang -target arm -mcpu=cortex-a57 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV8A %s
 // CHECK-CPUV8A: "-cc1"{{.*}} "-triple" "armv8-{{.*}}
 
 // RUN: %clang -target arm -mcpu=cortex-a53 -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV8A-THUMB %s
 // RUN: %clang -target arm -mcpu=cortex-a57 -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV8A-THUMB %s
 // CHECK-CPUV8A-THUMB: "-cc1"{{.*}} "-triple" "thumbv8-{{.*}}