[PATCH] D108933: [LegalizeTypes][X86] Improve ExpandIntRes_FP_TO_SINT/ExpandIntRes_FP_TO_UINT when input is SoftPromoteHalf.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: efriedma, RKSimon, compnerd, spatel.
Herald added subscribers: pengfei, hiraditya.
craig.topper requested review of this revision.
Herald added a project: LLVM.

Instead of splitting off the fp16 to float conversion and generating
a libcall, we should split the operation into fp16 to float and float
to integer operations. This will allow the float to integer conversion
to go through any custom handling the target has. If the target doesn't
have custom handling then we should come back to ExpandIntRes_FP_TO_SINT/
ExpandIntRes_FP_TO_UINT automatically to create the libcall.

This avoids generating libcalls on 32-bit X86. These library functions may
not exist in 32-bit libgcc. At least for LLVM, we never generate them when
hardware floating point instructions are available.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D108933

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
  llvm/test/CodeGen/X86/half.ll


Index: llvm/test/CodeGen/X86/half.ll
===================================================================
--- llvm/test/CodeGen/X86/half.ll
+++ llvm/test/CodeGen/X86/half.ll
@@ -210,14 +210,23 @@
 ;
 ; CHECK-I686-LABEL: test_fptosi_i64:
 ; CHECK-I686:       # %bb.0:
-; CHECK-I686-NEXT:    subl $12, %esp
+; CHECK-I686-NEXT:    subl $28, %esp
 ; CHECK-I686-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-I686-NEXT:    movzwl (%eax), %eax
 ; CHECK-I686-NEXT:    movl %eax, (%esp)
 ; CHECK-I686-NEXT:    calll __gnu_h2f_ieee
-; CHECK-I686-NEXT:    fstps (%esp)
-; CHECK-I686-NEXT:    calll __fixsfdi
-; CHECK-I686-NEXT:    addl $12, %esp
+; CHECK-I686-NEXT:    fstps {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    flds {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fnstcw {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    movzwl {{[0-9]+}}(%esp), %eax
+; CHECK-I686-NEXT:    orl $3072, %eax # imm = 0xC00
+; CHECK-I686-NEXT:    movw %ax, {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fldcw {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fistpll {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fldcw {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-I686-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; CHECK-I686-NEXT:    addl $28, %esp
 ; CHECK-I686-NEXT:    retl
   %a = load half, half* %p, align 2
   %r = fptosi half %a to i64
@@ -295,14 +304,35 @@
 ;
 ; CHECK-I686-LABEL: test_fptoui_i64:
 ; CHECK-I686:       # %bb.0:
-; CHECK-I686-NEXT:    subl $12, %esp
+; CHECK-I686-NEXT:    subl $28, %esp
 ; CHECK-I686-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-I686-NEXT:    movzwl (%eax), %eax
 ; CHECK-I686-NEXT:    movl %eax, (%esp)
 ; CHECK-I686-NEXT:    calll __gnu_h2f_ieee
-; CHECK-I686-NEXT:    fstps (%esp)
-; CHECK-I686-NEXT:    calll __fixunssfdi
-; CHECK-I686-NEXT:    addl $12, %esp
+; CHECK-I686-NEXT:    fstps {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; CHECK-I686-NEXT:    movss {{.*#+}} xmm1 = mem[0],zero,zero,zero
+; CHECK-I686-NEXT:    ucomiss %xmm1, %xmm0
+; CHECK-I686-NEXT:    jae .LBB9_2
+; CHECK-I686-NEXT:  # %bb.1:
+; CHECK-I686-NEXT:    xorps %xmm1, %xmm1
+; CHECK-I686-NEXT:  .LBB9_2:
+; CHECK-I686-NEXT:    subss %xmm1, %xmm0
+; CHECK-I686-NEXT:    movss %xmm0, {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    setae %al
+; CHECK-I686-NEXT:    flds {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fnstcw {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    movzwl {{[0-9]+}}(%esp), %ecx
+; CHECK-I686-NEXT:    orl $3072, %ecx # imm = 0xC00
+; CHECK-I686-NEXT:    movw %cx, {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fldcw {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fistpll {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    fldcw {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    movzbl %al, %edx
+; CHECK-I686-NEXT:    shll $31, %edx
+; CHECK-I686-NEXT:    xorl {{[0-9]+}}(%esp), %edx
+; CHECK-I686-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-I686-NEXT:    addl $28, %esp
 ; CHECK-I686-NEXT:    retl
   %a = load half, half* %p, align 2
   %r = fptoui half %a to i64
Index: llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -3093,6 +3093,9 @@
     EVT NFPVT = TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType());
     Op = GetSoftPromotedHalf(Op);
     Op = DAG.getNode(ISD::FP16_TO_FP, dl, NFPVT, Op);
+    Op = DAG.getNode(ISD::FP_TO_SINT, dl, VT, Op);
+    SplitInteger(Op, Lo, Hi);
+    return;
   }
 
   RTLIB::Libcall LC = RTLIB::getFPTOSINT(Op.getValueType(), VT);
@@ -3122,6 +3125,9 @@
     EVT NFPVT = TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType());
     Op = GetSoftPromotedHalf(Op);
     Op = DAG.getNode(ISD::FP16_TO_FP, dl, NFPVT, Op);
+    Op = DAG.getNode(ISD::FP_TO_UINT, dl, VT, Op);
+    SplitInteger(Op, Lo, Hi);
+    return;
   }
 
   RTLIB::Libcall LC = RTLIB::getFPTOUINT(Op.getValueType(), VT);


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