Author: statham Date: Mon Jun 3 04:02:53 2019 New Revision: 362380 URL: http://llvm.org/viewvc/llvm-project?rev=362380&view=rev Log: [ARM] Fix recent breakage of -mfpu=none.
The recent change D60691 introduced a bug in clang when handling option combinations such as `-mcpu=cortex-m4 -mfpu=none`. Those options together should select Cortex-M4 but disable all use of hardware FP, but in fact, now hardware FP instructions can still be generated in that mode. The reason is because the handling of FPUVersion::NONE disables all the same feature names it used to, of which the base one is `vfp2`. But now there are further features below that, like `vfp2d16fp` and (following D60694) `fpregs`, which also need to be turned off to disable hardware FP completely. Added a tiny test which double-checks that compiling a simple FP function doesn't access the FP registers. Reviewers: SjoerdMeijer, dmgreen Reviewed By: dmgreen Subscribers: lebedev.ri, javed.absar, kristof.beyls, hiraditya, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D62729 Added: cfe/trunk/test/CodeGen/arm-mfpu-none.c (with props) Modified: cfe/trunk/lib/Driver/ToolChains/Arch/ARM.cpp cfe/trunk/test/Driver/arm-mfpu.c Modified: cfe/trunk/lib/Driver/ToolChains/Arch/ARM.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/Arch/ARM.cpp?rev=362380&r1=362379&r2=362380&view=diff ============================================================================== --- cfe/trunk/lib/Driver/ToolChains/Arch/ARM.cpp (original) +++ cfe/trunk/lib/Driver/ToolChains/Arch/ARM.cpp Mon Jun 3 04:02:53 2019 @@ -430,8 +430,8 @@ fp16_fml_fallthrough: llvm::ARM::getFPUFeatures(llvm::ARM::FK_NONE, Features); // Disable hardware FP features which have been enabled. - // FIXME: Disabling vfp2 and neon should be enough as all the other - // features are dependent on these 2 features in LLVM. However + // FIXME: Disabling fpregs should be enough all by itself, since all + // the other FP features are dependent on it. However // there is currently no easy way to test this in clang, so for // now just be explicit and disable all known dependent features // as well. @@ -439,6 +439,11 @@ fp16_fml_fallthrough: "neon", "crypto", "dotprod", "fp16fml"}) if (std::find(std::begin(Features), std::end(Features), "+" + Feature) != std::end(Features)) Features.push_back(Args.MakeArgString("-" + Feature)); + + // Disable the base feature unconditionally, even if it was not + // explicitly in the features list (e.g. if we had +vfp3, which + // implies it). + Features.push_back("-fpregs"); } // En/disable crc code generation. Added: cfe/trunk/test/CodeGen/arm-mfpu-none.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/arm-mfpu-none.c?rev=362380&view=auto ============================================================================== --- cfe/trunk/test/CodeGen/arm-mfpu-none.c (added) +++ cfe/trunk/test/CodeGen/arm-mfpu-none.c Mon Jun 3 04:02:53 2019 @@ -0,0 +1,8 @@ +// REQUIRES: arm-registered-target +// RUN: %clang -target arm-none-eabi -mcpu=cortex-m4 -mfpu=none -S -o - %s | FileCheck %s + +// CHECK-LABEL: compute +// CHECK-NOT: {{s[0-9]}} +float compute(float a, float b) { + return (a+b) * (a-b); +} Propchange: cfe/trunk/test/CodeGen/arm-mfpu-none.c ------------------------------------------------------------------------------ svn:eol-style = native Propchange: cfe/trunk/test/CodeGen/arm-mfpu-none.c ------------------------------------------------------------------------------ svn:keywords = Rev Date Author URL Id Modified: cfe/trunk/test/Driver/arm-mfpu.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/arm-mfpu.c?rev=362380&r1=362379&r2=362380&view=diff ============================================================================== --- cfe/trunk/test/Driver/arm-mfpu.c (original) +++ cfe/trunk/test/Driver/arm-mfpu.c Mon Jun 3 04:02:53 2019 @@ -318,6 +318,7 @@ // RUN: | FileCheck --check-prefix=CHECK-NO-FP %s // CHECK-NO-FP-NOT: "-target-feature" "+soft-float" // CHECK-NO-FP: "-target-feature" "+soft-float-abi" +// CHECK-NO-FP: "-target-feature" "-fpregs" // CHECK-NO-FP: "-target-feature" "-vfp2" // CHECK-NO-FP: "-target-feature" "-vfp3" // CHECK-NO-FP: "-target-feature" "-vfp4" @@ -363,6 +364,7 @@ // CHECK-SOFT-ABI-FP: "-target-feature" "-fp-armv8" // CHECK-SOFT-ABI-FP: "-target-feature" "-neon" // CHECK-SOFT-ABI-FP: "-target-feature" "-crypto" +// CHECK-SOFT-ABI-FP: "-target-feature" "-fpregs" // RUN: %clang -target arm-linux-androideabi21 %s -### -c 2>&1 \ // RUN: | FileCheck --check-prefix=CHECK-ARM5-ANDROID-FP-DEFAULT %s _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
