[RISCV] Support -m[no-]strict-align options

[wangpc]

Summary

To match GCC.

Options -m[no-]strict-align are aliases of -m[no-]unaligned-access
in clang, but there is no corresponding option in GCC.

Support of -m[no-]unaligned-access in GCC may be needed to align
Clang/GCC.

[wangpc]

Add +unaligned-vector-mem if V exists.

[wangpc]

Remove includes.

[craig.topper]

Update ReleaseNotes?

[wangpc]

Update ReleaseNotes.

[arichardson]

clang/test/Driver/riscv-features.c

43

This looks a bit fragile, can we just check all -target-feature flags instead and add --implicit-check-not='-target-feature" to Filecheck?

[wangpc]

clang/test/Driver/riscv-features.c

43

I'm so sorry that I may not get what you mean, can you tell me what kind of change I need to make?

[kito-cheng]

LGTM

clang/test/Driver/riscv-features.c

43

I would suggest keep this check simple as it, because the -target-feature list for RISC-V is very loooooong, the list will increase when we add new extension, and add new extension is kind of relative frequently happened for RISC-V, check the full feature list will increase the maintenance burden for adding new extensions IMO.

e.g.

$ clang --target=riscv32-unknown-elf -### %s -march=rv32gv -mstrict-align ~/x.c
 "/scratch1/kitoc/llvm-workspace/build/bin/clang-18" "-cc1" "-triple" "riscv32-unknown-unknown-elf" "-emit-obj" "-mrelax-all" "-dumpdir" "a-" "-disable-free" "-clear-ast-before-backend" "-main-file-name" "x.c" "-mrelocation-model" "static" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-nostdsysteminc" "-target-cpu" "generic-rv32" "-target-feature" "+m" "-target-feature" "+a" "-target-feature" "+f" "-target-feature" "+d" "-target-feature" "+v" "-target-feature" "+zicsr" "-target-feature" "+zifencei" "-target-feature" "+zve32f" "-target-feature" "+zve32x" "-target-feature" "+zve64d" "-target-feature" "+zve64f" "-target-feature" "+zve64x" "-target-feature" "+zvl128b" "-target-feature" "+zvl32b" "-target-feature" "+zvl64b" "-target-feature" "-c" "-target-feature" "-e" "-target-feature" "-h" "-target-feature" "-svinval" "-target-feature" "-svnapot" "-target-feature" "-svpbmt" "-target-feature" "-xcvalu" "-target-feature" "-xcvbi" "-target-feature" "-xcvbitmanip" "-target-feature" "-xcvmac" "-target-feature" "-xcvsimd" "-target-feature" "-xsfcie" "-target-feature" "-xsfvcp" "-target-feature" "-xtheadba" "-target-feature" "-xtheadbb" "-target-feature" "-xtheadbs" "-target-feature" "-xtheadcmo" "-target-feature" "-xtheadcondmov" "-target-feature" "-xtheadfmemidx" "-target-feature" "-xtheadmac" "-target-feature" "-xtheadmemidx" "-target-feature" "-xtheadmempair" "-target-feature" "-xtheadsync" "-target-feature" "-xtheadvdot" "-target-feature" "-xventanacondops" "-target-feature" "-zawrs" "-target-feature" "-zba" "-target-feature" "-zbb" "-target-feature" "-zbc" "-target-feature" "-zbkb" "-target-feature" "-zbkc" "-target-feature" "-zbkx" "-target-feature" "-zbs" "-target-feature" "-zca" "-target-feature" "-zcb" "-target-feature" "-zcd" "-target-feature" "-zce" "-target-feature" "-zcf" "-target-feature" "-zcmp" "-target-feature" "-zcmt" "-target-feature" "-zdinx" "-target-feature" "-zfh" "-target-feature" "-zfhmin" "-target-feature" "-zfinx" "-target-feature" "-zhinx" "-target-feature" "-zhinxmin" "-target-feature" "-zicbom" "-target-feature" "-zicbop" "-target-feature" "-zicboz" "-target-feature" "-zicntr" "-target-feature" "-zihintpause" "-target-feature" "-zihpm" "-target-feature" "-zk" "-target-feature" "-zkn" "-target-feature" "-zknd" "-target-feature" "-zkne" "-target-feature" "-zknh" "-target-feature" "-zkr" "-target-feature" "-zks" "-target-feature" "-zksed" "-target-feature" "-zksh" "-target-feature" "-zkt" "-target-feature" "-zmmul" "-target-feature" "-zvfh" "-target-feature" "-zvl1024b" "-target-feature" "-zvl16384b" "-target-feature" "-zvl2048b" "-target-feature" "-zvl256b" "-target-feature" "-zvl32768b" "-target-feature" "-zvl4096b" "-target-feature" "-zvl512b" "-target-feature" "-zvl65536b" "-target-feature" "-zvl8192b" "-target-feature" "-experimental-smaia" "-target-feature" "-experimental-ssaia" "-target-feature" "-experimental-zacas" "-target-feature" "-experimental-zfa" "-target-feature" "-experimental-zfbfmin" "-target-feature" "-experimental-zicond" "-target-feature" "-experimental-zihintntl" "-target-feature" "-experimental-ztso" "-target-feature" "-experimental-zvbb" "-target-feature" "-experimental-zvbc" "-target-feature" "-experimental-zvfbfmin" "-target-feature" "-experimental-zvfbfwma" "-target-feature" "-experimental-zvkg" "-target-feature" "-experimental-zvkn" "-target-feature" "-experimental-zvknc" "-target-feature" "-experimental-zvkned" "-target-feature" "-experimental-zvkng" "-target-feature" "-experimental-zvknha" "-target-feature" "-experimental-zvknhb" "-target-feature" "-experimental-zvks" "-target-feature" "-experimental-zvksc" "-target-feature" "-experimental-zvksed" "-target-feature" "-experimental-zvksg" "-target-feature" "-experimental-zvksh" "-target-feature" "-experimental-zvkt" "-target-feature" "+relax" "-target-feature" "-save-restore" "-target-abi" "ilp32d" "-msmall-data-limit" "8" "-debugger-tuning=gdb" "-fcoverage-compilation-dir=/home/kitoc/llvm-workspace/llvm-project/clang/test" "-resource-dir" "/scratch1/kitoc/llvm-workspace/build/lib/clang/18" "-internal-isystem" "/scratch1/kitoc/llvm-workspace/build/lib/clang/18/include" "-internal-isystem" "/scratch1/kitoc/llvm-workspace/build/bin/../lib/clang-runtimes/riscv32-unknown-elf/include" "-fdebug-compilation-dir=/home/kitoc/llvm-workspace/llvm-project/clang/test" "-ferror-limit" "19" "-fno-signed-char" "-fgnuc-version=4.2.1" "-fcolor-diagnostics" "-faddrsig" "-o" "/tmp/x-83967d.o" "-x" "c" "/home/kitoc/x.c"
 "/home/kitoc/llvm-workspace/build/bin/ld.lld" "/tmp/x-83967d.o" "-Bstatic" "-L/scratch1/kitoc/llvm-workspace/build/bin/../lib/clang-runtimes/riscv32-unknown-elf/lib" "-L/scratch1/kitoc/llvm-workspace/build/bin/../lib/clang-runtimes/riscv32-unknown-elf/lib" "-L/scratch1/kitoc/llvm-workspace/build/lib/clang/18/lib/baremetal" "-lc" "-lm" "-lclang_rt.builtins-riscv32" "-X" "-o" "a.out"

[wangpc]

Thanks!

[wangpc]

Rebase since ReleaseNotes.rst is changed.

clang/docs/ReleaseNotes.rst

 Windows Support
 ^^^^^^^^^^^^^^^
 
 LoongArch Support
 ^^^^^^^^^^^^^^^^^
 
 RISC-V Support
 ^^^^^^^^^^^^^^
+- Unaligned memory accesses can be toggled by ``-m[no-]unaligned-access`` or the
+  aliases ``-m[no-]strict-align``.
 
 CUDA/HIP Language Changes
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 CUDA Support
 ^^^^^^^^^^^^
 
 AIX Support

clang/include/clang/Driver/Options.td

 def mrvv_vector_bits_EQ : Joined<["-"], "mrvv-vector-bits=">, Group<m_Group>,
   HelpText<"Specify the size in bits of an RVV vector register. Defaults to "
            "the vector length agnostic value of \"scalable\". Accepts power of "
            "2 values between 64 and 65536. Also accepts \"zvl\" "
            "to use the value implied by -march/-mcpu. Value will be reflected "
            "in __riscv_v_fixed_vlen preprocessor define (RISC-V only)">;
 
 def munaligned_access : Flag<["-"], "munaligned-access">, Group<m_Group>,
-  HelpText<"Allow memory accesses to be unaligned (AArch32/AArch64/LoongArch only)">;
+  HelpText<"Allow memory accesses to be unaligned (AArch32/AArch64/LoongArch/RISC-V only)">;
 def mno_unaligned_access : Flag<["-"], "mno-unaligned-access">, Group<m_Group>,
-  HelpText<"Force all memory accesses to be aligned (AArch32/AArch64/LoongArch only)">;
+  HelpText<"Force all memory accesses to be aligned (AArch32/AArch64/LoongArch/RISC-V only)">;
 } // let Flags = [TargetSpecific]
 def mstrict_align : Flag<["-"], "mstrict-align">, Alias<mno_unaligned_access>, Flags<[CC1Option,HelpHidden]>,
   HelpText<"Force all memory accesses to be aligned (same as mno-unaligned-access)">;
 def mno_strict_align : Flag<["-"], "mno-strict-align">, Alias<munaligned_access>, Flags<[CC1Option,HelpHidden]>,
   HelpText<"Allow memory accesses to be unaligned (same as munaligned-access)">;
 let Flags = [TargetSpecific] in {
 def mno_thumb : Flag<["-"], "mno-thumb">, Group<m_arm_Features_Group>;
 def mrestrict_it: Flag<["-"], "mrestrict-it">, Group<m_arm_Features_Group>,

clang/lib/Driver/ToolChains/Arch/RISCV.cpp

void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
 
   // GCC Compatibility: -mno-save-restore is default, unless -msave-restore is
   // specified.
   if (Args.hasFlag(options::OPT_msave_restore, options::OPT_mno_save_restore, false))
     Features.push_back("+save-restore");
   else
     Features.push_back("-save-restore");
 
+  // -mno-unaligned-access is default, unless -munaligned-access is specified.
+  bool HasV = llvm::is_contained(Features, "+zve32x");
+  if (Args.hasFlag(options::OPT_munaligned_access,
+                   options::OPT_mno_unaligned_access, false)) {
+    Features.push_back("+unaligned-scalar-mem");
+    if (HasV)
+      Features.push_back("+unaligned-vector-mem");
+  } else {
+    Features.push_back("-unaligned-scalar-mem");
+    if (HasV)
+      Features.push_back("-unaligned-vector-mem");
+  }
+
   // Now add any that the user explicitly requested on the command line,
   // which may override the defaults.
   handleTargetFeaturesGroup(D, Triple, Args, Features,
                             options::OPT_m_riscv_Features_Group);
 }
 
 StringRef riscv::getRISCVABI(const ArgList &Args, const llvm::Triple &Triple) {
   assert(Triple.isRISCV() && "Unexpected triple");

clang/test/Driver/riscv-default-features.c

 // RUN: %clang --target=riscv32-unknown-elf -S -emit-llvm %s -o - | FileCheck %s -check-prefix=RV32
 // RUN: %clang --target=riscv64-unknown-elf -S -emit-llvm %s -o - | FileCheck %s -check-prefix=RV64
 
 // RV32: "target-features"="+32bit,+a,+c,+m,+relax,
 // RV32-SAME: -save-restore
+// RV32-SAME: -unaligned-scalar-mem
 // RV64: "target-features"="+64bit,+a,+c,+m,+relax,
 // RV64-SAME: -save-restore
+// RV64-SAME: -unaligned-scalar-mem
 
 // Dummy function
 int foo(void){
   return  3;
 }

clang/test/Driver/riscv-features.c

 // RUN: %clang --target=riscv32-unknown-elf -### %s -msave-restore 2>&1 | FileCheck %s -check-prefix=SAVE-RESTORE
 // RUN: %clang --target=riscv32-unknown-elf -### %s -mno-save-restore 2>&1 | FileCheck %s -check-prefix=NO-SAVE-RESTORE
 
 // SAVE-RESTORE: "-target-feature" "+save-restore"
 // NO-SAVE-RESTORE: "-target-feature" "-save-restore"
 // DEFAULT: "-target-feature" "-save-restore"
 // DEFAULT-NOT: "-target-feature" "+save-restore"
 
+// RUN: %clang --target=riscv32-unknown-elf -### %s -munaligned-access 2>&1 | FileCheck %s -check-prefix=UNALIGNED-SCALAR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -mno-unaligned-access 2>&1 | FileCheck %s -check-prefix=NO-UNALIGNED-SCALAR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -mno-strict-align 2>&1 | FileCheck %s -check-prefix=UNALIGNED-SCALAR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -mstrict-align 2>&1 | FileCheck %s -check-prefix=NO-UNALIGNED-SCALAR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -march=rv32gv -munaligned-access 2>&1 | FileCheck %s -check-prefix=UNALIGNED-VECTOR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -march=rv32gv -mno-unaligned-access 2>&1 | FileCheck %s -check-prefix=NO-UNALIGNED-VECTOR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -march=rv32gv -mno-strict-align 2>&1 | FileCheck %s -check-prefix=UNALIGNED-VECTOR-MEM
+// RUN: %clang --target=riscv32-unknown-elf -### %s -march=rv32gv -mstrict-align 2>&1 | FileCheck %s -check-prefix=NO-UNALIGNED-VECTOR-MEM
+
+// UNALIGNED-SCALAR-MEM: "-target-feature" "+unaligned-scalar-mem"
+// NO-UNALIGNED-SCALAR-MEM: "-target-feature" "-unaligned-scalar-mem"
+// UNALIGNED-VECTOR-MEM: "-target-feature" "+unaligned-vector-mem"
+// NO-UNALIGNED-VECTOR-MEM: "-target-feature" "-unaligned-vector-mem"
+// DEFAULT: "-target-feature" "-unaligned-scalar-mem"
+// DEFAULT-NOT: "-target-feature" "+unaligned-scalar-mem"
+
 // RUN: %clang --target=riscv32-linux -### %s -fsyntax-only 2>&1 \
 // RUN:   | FileCheck %s -check-prefix=DEFAULT-LINUX
 // RUN: %clang --target=riscv64-linux -### %s -fsyntax-only 2>&1 \
 // RUN:   | FileCheck %s -check-prefix=DEFAULT-LINUX
 
 // DEFAULT-LINUX: "-funwind-tables=2"
 // DEFAULT-LINUX-SAME: "-target-feature" "+m"
 // DEFAULT-LINUX-SAME: "-target-feature" "+a"