[libcxx-commits] [llvm] [clang-tools-extra] [lldb] [libcxx] [clang] [flang] [mlir] [X86] Add "Ws" constraint and "p" modifier for symbolic address/label reference (PR #77886)

[Fangrui Song via libcxx-commits]

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@@ -0,0 +1,34 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=i686 < %s | FileCheck %s
+; RUN: llc -mtriple=x86_64 < %s | FileCheck %s
+
+ at var = external dso_local global i32, align 4
+
+define dso_local void @test() {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    # var test
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    ret{{[l|q]}}
+entry:
+  call void asm sideeffect "// ${0:p} ${1:p}", "^Ws,^Ws,~{dirflag},~{fpsr},~{flags}"(ptr @var, ptr @test)
+  ret void
+}
+
+define dso_local void @test_label() {
+; CHECK-LABEL: test_label:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:  .Ltmp0: # Block address taken
+; CHECK-NEXT:  # %bb.1: # %label
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    # .Ltmp0
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    ret{{[l|q]}}
+entry:
+  br label %label
+
+label:
+  tail call void asm sideeffect "// ${0:p}", "Ws,~{dirflag},~{fpsr},~{flags}"(ptr blockaddress(@test_label, %label))
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MaskRay wrote:

Thanks for spotting this. Fixed.

I think constraint validation is primarily performed in Clang Sema and it's easy to crash LLVM with invalid LLVM IR. In this case Ws+0:p happens to work as well.

https://github.com/llvm/llvm-project/pull/77886