[CodeGen] Add thumb-mode to target-features for arm/thumb triples.

[fhahn]

Summary

The thumb-mode target feature is used to force Thumb or ARM code
generation on a per-function basis. Explicitly adding +thumb-mode to
functions for thumbxx triples enables mixed ARM/Thumb code generation in
places where compilation units with thumbxx and armxx triples are merged
together (e.g. the IR linker or LTO).

For armxx triples, -thumb-mode is added in a similar fashion.

[echristo]

I probably would have added this as a feature in ARMTargetInfo similar to CRC/soft-float/etc.

Thoughts?

-eric

[fhahn]

In D33448#762410, @echristo wrote:

I probably would have added this as a feature in ARMTargetInfo similar to CRC/soft-float/etc.

Thoughts?

Do you mean ARMTargetMachine::getSubtargetImpl (https://github.com/llvm-mirror/llvm/blob/master/lib/Target/ARM/ARMTargetMachine.cpp#L305) ?

It seems like that function is only used by llc (and not llvm-as for example) and at that stage it is too late to add thumb-mode, because llc operates on a single module with a single target triple.

[echristo]

In D33448#763411, @fhahn wrote:

In D33448#762410, @echristo wrote:

I probably would have added this as a feature in ARMTargetInfo similar to CRC/soft-float/etc.

Thoughts?

Do you mean ARMTargetMachine::getSubtargetImpl (https://github.com/llvm-mirror/llvm/blob/master/lib/Target/ARM/ARMTargetMachine.cpp#L305) ?

It seems like that function is only used by llc (and not llvm-as for example) and at that stage it is too late to add thumb-mode, because llc operates on a single module with a single target triple.

No, I meant somewhere around here: https://github.com/llvm-mirror/clang/blob/master/lib/Basic/Targets.cpp#L5058 to define it and then in CGCall.cpp it'll get added along with the other target-features.

I think that'll enable you to handle -mthumb and -target in a fairly unified way?

[fhahn]

Move code to lib/Basic/Targets.cpp

[fhahn]

@echristo lib/Basic/Targets.cpp is indeed a much better place to add thumb-mode to the target features, thanks for pointing me in the right direction!

[echristo]

One minor nit and LGTM.

Thanks!

-eric

lib/Basic/Targets.cpp

5441

Minor nit: comments are full sentences.

[fhahn]

Updated the comment, thanks for the reviewing this patch!

[fhahn]

I'll hold off merging this patch until D33436 lands, which fixes a problem with mixed ARM/Thumb codegen

[echristo]

In D33448#765749, @fhahn wrote:

I'll hold off merging this patch until D33436 lands, which fixes a problem with mixed ARM/Thumb codegen

OK. Commit at will :)

-eric

[fhahn]

I've discovered another problem while doing an ARM bootstrap build with mixed ARM/Thumb codegen. With D33898 , the bootstrap build with mixed ARM/Thumb code works properly. After that's in I'll finally commit this patch.

[fhahn]

rebased

lib/Basic/Targets.cpp

initFeatureMap(llvm::StringMap<bool> &Features, DiagnosticsEngine &Diags,
     // get default Extension features
     unsigned Extensions = llvm::ARM::getDefaultExtensions(CPU, Arch);
     llvm::ARM::getExtensionFeatures(Extensions, TargetFeatures);
 
     for (auto Feature : TargetFeatures)
       if (Feature[0] == '+')
         Features[Feature.drop_front(1)] = true;
 
+    // Enable or disable thumb-mode explicitly per function to enable mixed
+    // ARM and Thumb code generation.
+    if (isThumb())
+      Features["thumb-mode"] = true;
+    else
+      Features["thumb-mode"] = false;
+
     // Convert user-provided arm and thumb GNU target attributes to
     // [-|+]thumb-mode target features respectively.
     std::vector<std::string> UpdatedFeaturesVec(FeaturesVec);
     for (auto &Feature : UpdatedFeaturesVec) {
       if (Feature.compare("+arm") == 0)
         Feature = "-thumb-mode";
       else if (Feature.compare("+thumb") == 0)
         Feature = "+thumb-mode";

test/CodeGen/arm-long-calls.c

 // RUN: %clang_cc1 -triple thumbv7-apple-ios5  -target-feature +long-calls -emit-llvm -o - %s | FileCheck -check-prefix=LONGCALL %s
 // RUN: %clang_cc1 -triple thumbv7-apple-ios5 -emit-llvm -o - %s | FileCheck -check-prefix=NOLONGCALL %s
 
-// LONGCALL: attributes #0 = { {{.*}} "target-features"="+long-calls"
-// NOLONGCALL-NOT: attributes #0 = { {{.*}} "target-features"="+long-calls"
+// LONGCALL: attributes #0 = { {{.*}} "target-features"="+long-calls,+thumb-mode"
+// NOLONGCALL-NOT: attributes #0 = { {{.*}} "target-features"="+long-calls,+thumb-mode"
 
 int foo1(int a) { return a; }

test/CodeGen/arm-no-movt.c

 // RUN: %clang_cc1 -triple thumbv7-apple-ios5  -target-feature +no-movt -emit-llvm -o - %s | FileCheck -check-prefix=NO-MOVT %s
 // RUN: %clang_cc1 -triple thumbv7-apple-ios5 -emit-llvm -o - %s | FileCheck -check-prefix=MOVT %s
 
-// NO-MOVT: attributes #0 = { {{.*}} "target-features"="+no-movt"
-// MOVT-NOT: attributes #0 = { {{.*}} "target-features"="+no-movt"
+// NO-MOVT: attributes #0 = { {{.*}} "target-features"="+no-movt,+thumb-mode"
+// MOVT-NOT: attributes #0 = { {{.*}} "target-features"="+no-movt,+thumb-mode"
 
 int foo1(int a) { return a; }

test/CodeGen/arm-target-features.c

 // REQUIRES: arm-registered-target
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabihf -target-cpu cortex-a8 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP3
-// CHECK-VFP3: "target-features"="+dsp,+neon,+vfp3"
-
-
-// RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-a9 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP3-FP16
-// CHECK-VFP3-FP16: "target-features"="+dsp,+fp16,+neon,+vfp3"
+// CHECK-VFP3: "target-features"="+dsp,+neon,+thumb-mode
 
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabihf -target-cpu cortex-a5 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4
-// CHECK-VFP4: "target-features"="+dsp,+neon,+vfp4"
+// CHECK-VFP4: "target-features"="+dsp,+neon,+thumb-mode,+vfp4"
 
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabihf -target-cpu cortex-a7 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-a12 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV
-// RUN: %clang_cc1 -triple armv7-linux-gnueabihf -target-cpu cortex-a15 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV
-// RUN: %clang_cc1 -triple armv7-linux-gnueabihf -target-cpu cortex-a17 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV
 // RUN: %clang_cc1 -triple thumbv7s-linux-gnueabi -target-cpu swift -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabihf -target-cpu krait -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV
-// CHECK-VFP4-DIV: "target-features"="+dsp,+hwdiv,+hwdiv-arm,+neon,+vfp4"
+// CHECK-VFP4-DIV: "target-features"="+dsp,+hwdiv,+hwdiv-arm,+neon,+thumb-mode,+vfp4"
 
+// RUN: %clang_cc1 -triple armv7-linux-gnueabihf -target-cpu cortex-a15 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV-ARM
+// RUN: %clang_cc1 -triple armv7-linux-gnueabihf -target-cpu cortex-a17 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-DIV-ARM
+// CHECK-VFP4-DIV-ARM: "target-features"="+dsp,+hwdiv,+hwdiv-arm,+neon,+vfp4,-thumb-mode"
 
 // RUN: %clang_cc1 -triple thumbv7s-apple-ios7.0 -target-cpu cyclone -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu cortex-a32 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu cortex-a35 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
-// RUN: %clang_cc1 -triple armv8-linux-gnueabi -target-cpu cortex-a53 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu cortex-a57 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu cortex-a72 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu cortex-a73 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu exynos-m1 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu exynos-m2 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
 // RUN: %clang_cc1 -triple thumbv8-linux-gnueabihf -target-cpu exynos-m3 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8
-// CHECK-BASIC-V8: "target-features"="+crc,+crypto,+dsp,+fp-armv8,+hwdiv,+hwdiv-arm,+neon"
+// CHECK-BASIC-V8: "target-features"="+crc,+crypto,+dsp,+fp-armv8,+hwdiv,+hwdiv-arm,+neon,+thumb-mode"
 
+// RUN: %clang_cc1 -triple armv8-linux-gnueabi -target-cpu cortex-a53 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-BASIC-V8-ARM
+// CHECK-BASIC-V8-ARM: "target-features"="+crc,+crypto,+dsp,+fp-armv8,+hwdiv,+hwdiv-arm,+neon,-thumb-mode"
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-r5 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP3-D16-DIV
-// CHECK-VFP3-D16-DIV: "target-features"="+d16,+dsp,+hwdiv,+hwdiv-arm,+vfp3"
+// CHECK-VFP3-D16-DIV: "target-features"="+d16,+dsp,+hwdiv,+hwdiv-arm,+thumb-mode,+vfp3"
 
 
 // RUN: %clang_cc1 -triple armv7-linux-gnueabi -target-cpu cortex-r4f -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP3-D16-THUMB-DIV
-// CHECK-VFP3-D16-THUMB-DIV: "target-features"="+d16,+dsp,+hwdiv,+vfp3"
+// CHECK-VFP3-D16-THUMB-DIV: "target-features"="+d16,+dsp,+hwdiv,+vfp3,-thumb-mode"
 
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-r7 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP3-D16-FP16-DIV
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-r8 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP3-D16-FP16-DIV
-// CHECK-VFP3-D16-FP16-DIV: "target-features"="+d16,+dsp,+fp16,+hwdiv,+hwdiv-arm,+vfp3"
+// CHECK-VFP3-D16-FP16-DIV: "target-features"="+d16,+dsp,+fp16,+hwdiv,+hwdiv-arm,+thumb-mode,+vfp3"
 
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-m4 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP4-D16-SP-THUMB-DIV
-// CHECK-VFP4-D16-SP-THUMB-DIV: "target-features"="+d16,+dsp,+fp-only-sp,+hwdiv,+vfp4"
+// CHECK-VFP4-D16-SP-THUMB-DIV: "target-features"="+d16,+dsp,+fp-only-sp,+hwdiv,+thumb-mode,+vfp4"
 
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-m7 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-VFP5-D16-THUMB-DIV
-// CHECK-VFP5-D16-THUMB-DIV: "target-features"="+d16,+dsp,+fp-armv8,+hwdiv"
+// CHECK-VFP5-D16-THUMB-DIV: "target-features"="+d16,+dsp,+fp-armv8,+hwdiv,+thumb-mode"
 
 
 // RUN: %clang_cc1 -triple armv7-linux-gnueabi -target-cpu cortex-r4 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-THUMB-DIV
-// CHECK-THUMB-DIV: "target-features"="+dsp,+hwdiv"
+// CHECK-THUMB-DIV: "target-features"="+dsp,+hwdiv,-thumb-mode"
 
 // RUN: %clang_cc1 -triple thumbv7-linux-gnueabi -target-cpu cortex-m3 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-THUMB-DIV-M3
-// CHECK-THUMB-DIV-M3: "target-features"="+hwdiv"
+// CHECK-THUMB-DIV-M3: "target-features"="+hwdiv,+thumb-mode"
 
 
 void foo() {}

test/CodeGen/arm-thumb-mode-target-feature.c

+// REQUIRES: arm-registered-target
+
+// RUN: %clang_cc1 -triple thumbv7-linux-gnueabihf -emit-llvm -o - %s | FileCheck --check-prefix THUMB %s
+// RUN: %clang_cc1 -triple thumbv7eb-linux-gnueabihf -emit-llvm -o - %s | FileCheck --check-prefix THUMB %s
+// RUN: %clang -target armv7-linux-gnueabihf -mthumb -S -emit-llvm -o - %s | FileCheck --check-prefix THUMB-CLANG %s
+// RUN: %clang_cc1 -triple armv7-linux-gnueabihf -emit-llvm -o - %s | FileCheck --check-prefix ARM %s
+// RUN: %clang_cc1 -triple armv7eb-linux-gnueabihf -emit-llvm -o - %s | FileCheck --check-prefix ARM %s
+
+void t1() {}
+
+ __attribute__((target("no-thumb-mode")))
+void t2() {}
+
+ __attribute__((target("thumb-mode")))
+void t3() {}
+
+// THUMB: void @t1() [[ThumbAttr:#[0-7]]]
+// THUMB: void @t2() [[NoThumbAttr:#[0-7]]]
+// THUMB: void @t3() [[ThumbAttr:#[0-7]]]
+// THUMB: attributes [[ThumbAttr]] = { {{.*}} "target-features"="+thumb-mode"
+// THUMB: attributes [[NoThumbAttr]] = { {{.*}} "target-features"="-thumb-mode"
+//
+// THUMB-CLANG: void @t1() [[ThumbAttr:#[0-7]]]
+// THUMB-CLANG: void @t2() [[NoThumbAttr:#[0-7]]]
+// THUMB-CLANG: void @t3() [[ThumbAttr:#[0-7]]]
+// THUMB-CLANG: attributes [[ThumbAttr]] = { {{.*}} "target-features"="{{.*}}+thumb-mode
+// THUMB-CLANG: attributes [[NoThumbAttr]] = { {{.*}} "target-features"="{{.*}}-thumb-mode
+
+// ARM: void @t1() [[NoThumbAtr:#[0-7]]]
+// ARM: void @t2() [[NoThumbAttr:#[0-7]]]
+// ARM: void @t3() [[ThumbAttr:#[0-7]]]
+// ARM: attributes [[NoThumbAttr]] = { {{.*}} "target-features"="-thumb-mode"
+// ARM: attributes [[ThumbAttr]] = { {{.*}} "target-features"="+thumb-mode"