Revert "[X86][BF16] Add libcall for F80 -> BF16 (#109116)"

This reverts commit 76eda76.

Author: phoebewang

compiler-rt/lib/builtins/CMakeLists.txt

@@ -192,7 +192,6 @@ set(GENERIC_SOURCES
 set(BF16_SOURCES
     extendbfsf2.c
     truncdfbf2.c
-    truncxfbf2.c
     truncsfbf2.c
 )
 

compiler-rt/lib/builtins/truncxfbf2.c

@@ -367,7 +367,6 @@ HANDLE_LIBCALL(FPROUND_F128_F16, "__trunctfhf2")
 HANDLE_LIBCALL(FPROUND_PPCF128_F16, "__trunctfhf2")
 HANDLE_LIBCALL(FPROUND_F32_BF16, "__truncsfbf2")
 HANDLE_LIBCALL(FPROUND_F64_BF16, "__truncdfbf2")
-HANDLE_LIBCALL(FPROUND_F80_BF16, "__truncxfbf2")
 HANDLE_LIBCALL(FPROUND_F64_F32, "__truncdfsf2")
 HANDLE_LIBCALL(FPROUND_F80_F32, "__truncxfsf2")
 HANDLE_LIBCALL(FPROUND_F128_F32, "__trunctfsf2")

llvm/include/llvm/IR/RuntimeLibcalls.def

@@ -169,8 +169,6 @@ RTLIB::Libcall RTLIB::getFPROUND(EVT OpVT, EVT RetVT) {
       return FPROUND_F32_BF16;
     if (OpVT == MVT::f64)
       return FPROUND_F64_BF16;
-    if (OpVT == MVT::f80)
-      return FPROUND_F80_BF16;
   } else if (RetVT == MVT::f32) {
     if (OpVT == MVT::f64)
       return FPROUND_F64_F32;

llvm/lib/CodeGen/TargetLoweringBase.cpp

@@ -1953,25 +1953,3 @@ define void @PR92471(ptr %0, ptr %1) nounwind {
   store <7 x float> %4, ptr %1, align 4
   ret void
 }
-
-define bfloat @PR108936(x86_fp80 %0) nounwind {
-; X86-LABEL: PR108936:
-; X86:       # %bb.0:
-; X86-NEXT:    subl $12, %esp
-; X86-NEXT:    fldt {{[0-9]+}}(%esp)
-; X86-NEXT:    fstpt (%esp)
-; X86-NEXT:    calll __truncxfbf2
-; X86-NEXT:    addl $12, %esp
-; X86-NEXT:    retl
-;
-; CHECK-LABEL: PR108936:
-; CHECK:       # %bb.0:
-; CHECK-NEXT:    subq $24, %rsp
-; CHECK-NEXT:    fldt {{[0-9]+}}(%rsp)
-; CHECK-NEXT:    fstpt (%rsp)
-; CHECK-NEXT:    callq __truncxfbf2@PLT
-; CHECK-NEXT:    addq $24, %rsp
-; CHECK-NEXT:    retq
-  %2 = fptrunc x86_fp80 %0 to bfloat
-  ret bfloat %2
-}