[clang] [llvm] [Driver,CodeGen] Report error when enabling 64-bit-only features on non-64-bit arch (PR #101151)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-x86

@llvm/pr-subscribers-clang-driver

Author: Shengchen Kan (KanRobert)

<details>
<summary>Changes</summary>

In front-end, now we detect for `-mapx-features=/-mapxf` and `-muintr`, which is aligned with GCC

https://gcc.gnu.org/bugzilla/attachment.cgi?id=58698&action=diff

In backend, we just disable these 64-bit-only features silently, so that there is no error for
`-march=native -m32` on APX-supported arch.

llvm-issue: https://github.com/llvm/llvm-project/issues/94810
GCC thread: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115978

---
Full diff: https://github.com/llvm/llvm-project/pull/101151.diff


4 Files Affected:

- (modified) clang/lib/Driver/ToolChains/Arch/X86.cpp (+18-3) 
- (modified) clang/test/Driver/x86-target-features.c (+9-2) 
- (modified) llvm/lib/Target/X86/X86Subtarget.cpp (+7) 
- (added) llvm/test/CodeGen/X86/apx/i386-ndd.ll (+15) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/Arch/X86.cpp b/clang/lib/Driver/ToolChains/Arch/X86.cpp
index 2f63333b732f6..ef2c748694f09 100644
--- a/clang/lib/Driver/ToolChains/Arch/X86.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/X86.cpp
@@ -248,6 +248,10 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
     Features.push_back(Args.MakeArgString((IsNegative ? "-" : "+") + Name));
   }
 
+  llvm::StringSet<> SubFeaturesOfAPX = {"egpr", "push2pop2", "ppx", "ndd",
+                                        "ccmp", "nf",        "cf",  "zu"};
+  llvm::StringSet<> FeaturesIn64BitOnly = {"uintr"};
+  FeaturesIn64BitOnly.insert(SubFeaturesOfAPX.begin(), SubFeaturesOfAPX.end());
   // Now add any that the user explicitly requested on the command line,
   // which may override the defaults.
   for (const Arg *A : Args.filtered(options::OPT_m_x86_Features_Group,
@@ -266,13 +270,24 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
     }
 
     bool IsNegative = Name.starts_with("no-");
+
+    bool Not64Bit = ArchType != llvm::Triple::x86_64;
+    if (Not64Bit && FeaturesIn64BitOnly.contains(Name))
+      D.Diag(diag::err_drv_unsupported_opt_for_target)
+          << A->getSpelling() << Triple.getTriple();
+
     if (A->getOption().matches(options::OPT_mapx_features_EQ) ||
         A->getOption().matches(options::OPT_mno_apx_features_EQ)) {
 
       for (StringRef Value : A->getValues()) {
-        if (Value == "egpr" || Value == "push2pop2" || Value == "ppx" ||
-            Value == "ndd" || Value == "ccmp" || Value == "nf" ||
-            Value == "cf" || Value == "zu") {
+        if (SubFeaturesOfAPX.contains(Value)) {
+          if (Not64Bit && FeaturesIn64BitOnly.contains(Value)) {
+            std::string ArgOrAlias = A->getSpelling().str() + "|-mapxf";
+            D.Diag(diag::err_drv_unsupported_opt_for_target)
+                << ArgOrAlias << Triple.getTriple();
+            break;
+          }
+
           Features.push_back(
               Args.MakeArgString((IsNegative ? "-" : "+") + Value));
           continue;
diff --git a/clang/test/Driver/x86-target-features.c b/clang/test/Driver/x86-target-features.c
index 63237cbc3e7ef..99f81a869f0ee 100644
--- a/clang/test/Driver/x86-target-features.c
+++ b/clang/test/Driver/x86-target-features.c
@@ -309,8 +309,8 @@
 // HRESET: "-target-feature" "+hreset"
 // NO-HRESET: "-target-feature" "-hreset"
 
-// RUN: %clang --target=i386 -march=i386 -muintr %s -### 2>&1 | FileCheck -check-prefix=UINTR %s
-// RUN: %clang --target=i386 -march=i386 -mno-uintr %s -### 2>&1 | FileCheck -check-prefix=NO-UINTR %s
+// RUN: %clang --target=x86_64 -muintr %s -### 2>&1 | FileCheck -check-prefix=UINTR %s
+// RUN: %clang --target=x86_64 -mno-uintr %s -### 2>&1 | FileCheck -check-prefix=NO-UINTR %s
 // UINTR: "-target-feature" "+uintr"
 // NO-UINTR: "-target-feature" "-uintr"
 
@@ -409,6 +409,13 @@
 // NONX86-NEXT: warning: argument unused during compilation: '-msse4.2' [-Wunused-command-line-argument]
 // NONX86-NEXT: error: unsupported option '-mno-sgx' for target 'aarch64'
 
+// RUN: not %clang -### --target=i386 -muintr %s 2>&1 | FileCheck --check-prefix=NON-UINTR %s
+// RUN: not %clang -### --target=i386 -mapx-features=ndd %s 2>&1 | FileCheck --check-prefix=NON-APX %s
+// RUN: not %clang -### --target=i386 -mapxf %s 2>&1 | FileCheck --check-prefix=NON-APX %s
+// NON-UINTR:    error: unsupported option '-muintr' for target 'i386'
+// NON-APX:      error: unsupported option '-mapx-features=|-mapxf' for target 'i386'
+// NON-APX-NOT:  error: {{.*}} -mapx-features=
+
 // RUN: %clang --target=i386 -march=i386 -mharden-sls=return %s -### -o %t.o 2>&1 | FileCheck -check-prefixes=SLS-RET,NO-SLS %s
 // RUN: %clang --target=i386 -march=i386 -mharden-sls=indirect-jmp %s -### -o %t.o 2>&1 | FileCheck -check-prefixes=SLS-IJMP,NO-SLS %s
 // RUN: %clang --target=i386 -march=i386 -mharden-sls=none -mharden-sls=all %s -### -o %t.o 2>&1 | FileCheck -check-prefixes=SLS-IJMP,SLS-RET %s
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index 4e8e04b1112c0..7d5af2ede99cf 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -279,6 +279,13 @@ void X86Subtarget::initSubtargetFeatures(StringRef CPU, StringRef TuneCPU,
         FullFS += ",+evex512";
   }
 
+  // Disable 64-bit only features in non-64-bit mode.
+  SmallVector<StringRef, 9> FeaturesIn64BitOnly = {
+      "egpr", "push2pop2", "ppx", "ndd", "ccmp", "nf", "cf", "zu", "uintr"};
+  if (FullFS.find("-64bit-mode") != std::string::npos)
+    llvm::for_each(FeaturesIn64BitOnly,
+                   [&](StringRef F) { FullFS += ",-" + F.str(); });
+
   // Parse features string and set the CPU.
   ParseSubtargetFeatures(CPU, TuneCPU, FullFS);
 
diff --git a/llvm/test/CodeGen/X86/apx/i386-ndd.ll b/llvm/test/CodeGen/X86/apx/i386-ndd.ll
new file mode 100644
index 0000000000000..146a99340eb66
--- /dev/null
+++ b/llvm/test/CodeGen/X86/apx/i386-ndd.ll
@@ -0,0 +1,15 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=i386-linux-gnu -mattr=+cmov,+ndd < %s | FileCheck %s
+define i32 @test(i1 %cmp, i32 %x, i32 %y) nounwind {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    testb $1, {{[0-9]+}}(%esp)
+; CHECK-NEXT:    leal {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    leal {{[0-9]+}}(%esp), %ecx
+; CHECK-NEXT:    cmovnel %eax, %ecx
+; CHECK-NEXT:    movl (%ecx), %eax
+; CHECK-NEXT:    retl
+entry:
+  %cmov = select i1 %cmp, i32 %x, i32 %y
+  ret i32 %cmov
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/101151