Index: lib/Target/X86/X86LegalizerInfo.cpp
===================================================================
--- lib/Target/X86/X86LegalizerInfo.cpp
+++ lib/Target/X86/X86LegalizerInfo.cpp
@@ -211,6 +211,13 @@
     setAction({extOp, s64}, Legal);
   }
 
+  getActionDefinitionsBuilder(G_SITOFP)
+    .legalForCartesianProduct({s32, s64})
+      .clampScalar(1, s32, s64)
+      .widenScalarToNextPow2(1)
+      .clampScalar(0, s32, s64)
+      .widenScalarToNextPow2(0);
+
   // Comparison
   setAction({G_ICMP, 1, s64}, Legal);
 
Index: lib/Target/X86/X86RegisterBankInfo.cpp
===================================================================
--- lib/Target/X86/X86RegisterBankInfo.cpp
+++ lib/Target/X86/X86RegisterBankInfo.cpp
@@ -198,6 +198,17 @@
     // Instruction having only floating-point operands (all scalars in VECRReg)
     getInstrPartialMappingIdxs(MI, MRI, /* isFP */ true, OpRegBankIdx);
     break;
+  case TargetOpcode::G_SITOFP: {
+    // Some of the floating-point instructions have mixed GPR and FP operands:
+    // fine-tune the computed mapping.
+    auto &Op0 = MI.getOperand(0);
+    auto &Op1 = MI.getOperand(1);
+    const LLT Ty0 = MRI.getType(Op0.getReg());
+    const LLT Ty1 = MRI.getType(Op1.getReg());
+    OpRegBankIdx[0] = getPartialMappingIdx(Ty0, /* isFP */ true);
+    OpRegBankIdx[1] = getPartialMappingIdx(Ty1, /* isFP */ false);
+    break;
+  }
   case TargetOpcode::G_TRUNC:
   case TargetOpcode::G_ANYEXT: {
     auto &Op0 = MI.getOperand(0);
Index: test/CodeGen/X86/GlobalISel/regbankselect-X86_64.mir
===================================================================
--- test/CodeGen/X86/GlobalISel/regbankselect-X86_64.mir
+++ test/CodeGen/X86/GlobalISel/regbankselect-X86_64.mir
@@ -242,6 +242,30 @@
     ret void
   }
 
+  define float @int32_to_float(i32 %a) {
+  entry:
+    %conv = sitofp i32 %a to float
+    ret float %conv
+  }
+
+  define float @int64_to_float(i64 %a) {
+  entry:
+    %conv = sitofp i64 %a to float
+    ret float %conv
+  }
+
+  define double @int32_to_double(i32 %a) {
+  entry:
+    %conv = sitofp i32 %a to double
+    ret double %conv
+  }
+
+  define double @int64_to_double(i64 %a) {
+  entry:
+    %conv = sitofp i64 %a to double
+    ret double %conv
+  }
+
 ...
 ---
 name:            test_add_i8
@@ -1817,4 +1841,141 @@
     ; GREEDY: [[C1:%[0-9]+]]:vecr(s64) = G_FCONSTANT double 2.000000e+00
     %0(s32) = G_FCONSTANT float 1.0
     %1(s64) = G_FCONSTANT double 2.0
+
+...
+---
+name:            int32_to_float
+alignment:       4
+legalized:       true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; FAST-LABEL: name: int32_to_float
+    ; FAST: liveins: $edi
+    ; FAST: [[COPY:%[0-9]+]]:gpr(s32) = COPY $edi
+    ; FAST: [[SITOFP:%[0-9]+]]:vecr(s32) = G_SITOFP [[COPY]](s32)
+    ; FAST: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; FAST: $xmm0 = COPY [[ANYEXT]](s128)
+    ; FAST: RET 0, implicit $xmm0
+    ; GREEDY-LABEL: name: int32_to_float
+    ; GREEDY: liveins: $edi
+    ; GREEDY: [[COPY:%[0-9]+]]:gpr(s32) = COPY $edi
+    ; GREEDY: [[SITOFP:%[0-9]+]]:vecr(s32) = G_SITOFP [[COPY]](s32)
+    ; GREEDY: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; GREEDY: $xmm0 = COPY [[ANYEXT]](s128)
+    ; GREEDY: RET 0, implicit $xmm0
+    %0:_(s32) = COPY $edi
+    %1:_(s32) = G_SITOFP %0(s32)
+    %2:_(s128) = G_ANYEXT %1(s32)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int64_to_float
+alignment:       4
+legalized:       true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $rdi
+
+    ; FAST-LABEL: name: int64_to_float
+    ; FAST: liveins: $rdi
+    ; FAST: [[COPY:%[0-9]+]]:gpr(s64) = COPY $rdi
+    ; FAST: [[SITOFP:%[0-9]+]]:vecr(s32) = G_SITOFP [[COPY]](s64)
+    ; FAST: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; FAST: $xmm0 = COPY [[ANYEXT]](s128)
+    ; FAST: RET 0, implicit $xmm0
+    ; GREEDY-LABEL: name: int64_to_float
+    ; GREEDY: liveins: $rdi
+    ; GREEDY: [[COPY:%[0-9]+]]:gpr(s64) = COPY $rdi
+    ; GREEDY: [[SITOFP:%[0-9]+]]:vecr(s32) = G_SITOFP [[COPY]](s64)
+    ; GREEDY: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; GREEDY: $xmm0 = COPY [[ANYEXT]](s128)
+    ; GREEDY: RET 0, implicit $xmm0
+    %0:_(s64) = COPY $rdi
+    %1:_(s32) = G_SITOFP %0(s64)
+    %2:_(s128) = G_ANYEXT %1(s32)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int32_to_double
+alignment:       4
+legalized:       true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; FAST-LABEL: name: int32_to_double
+    ; FAST: liveins: $edi
+    ; FAST: [[COPY:%[0-9]+]]:gpr(s32) = COPY $edi
+    ; FAST: [[SITOFP:%[0-9]+]]:vecr(s64) = G_SITOFP [[COPY]](s32)
+    ; FAST: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; FAST: $xmm0 = COPY [[ANYEXT]](s128)
+    ; FAST: RET 0, implicit $xmm0
+    ; GREEDY-LABEL: name: int32_to_double
+    ; GREEDY: liveins: $edi
+    ; GREEDY: [[COPY:%[0-9]+]]:gpr(s32) = COPY $edi
+    ; GREEDY: [[SITOFP:%[0-9]+]]:vecr(s64) = G_SITOFP [[COPY]](s32)
+    ; GREEDY: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; GREEDY: $xmm0 = COPY [[ANYEXT]](s128)
+    ; GREEDY: RET 0, implicit $xmm0
+    %0:_(s32) = COPY $edi
+    %1:_(s64) = G_SITOFP %0(s32)
+    %2:_(s128) = G_ANYEXT %1(s64)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int64_to_double
+alignment:       4
+legalized:       true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $rdi
+
+    ; FAST-LABEL: name: int64_to_double
+    ; FAST: liveins: $rdi
+    ; FAST: [[COPY:%[0-9]+]]:gpr(s64) = COPY $rdi
+    ; FAST: [[SITOFP:%[0-9]+]]:vecr(s64) = G_SITOFP [[COPY]](s64)
+    ; FAST: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; FAST: $xmm0 = COPY [[ANYEXT]](s128)
+    ; FAST: RET 0, implicit $xmm0
+    ; GREEDY-LABEL: name: int64_to_double
+    ; GREEDY: liveins: $rdi
+    ; GREEDY: [[COPY:%[0-9]+]]:gpr(s64) = COPY $rdi
+    ; GREEDY: [[SITOFP:%[0-9]+]]:vecr(s64) = G_SITOFP [[COPY]](s64)
+    ; GREEDY: [[ANYEXT:%[0-9]+]]:vecr(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; GREEDY: $xmm0 = COPY [[ANYEXT]](s128)
+    ; GREEDY: RET 0, implicit $xmm0
+    %0:_(s64) = COPY $rdi
+    %1:_(s64) = G_SITOFP %0(s64)
+    %2:_(s128) = G_ANYEXT %1(s64)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
 ...
Index: test/CodeGen/X86/GlobalISel/x86_64-legalize-sitofp.mir
===================================================================
--- /dev/null
+++ test/CodeGen/X86/GlobalISel/x86_64-legalize-sitofp.mir
@@ -0,0 +1,306 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=x86_64-linux-gnu -global-isel -run-pass=legalizer -verify-machineinstrs %s -o - | FileCheck %s
+
+--- |
+  ; ModuleID = 'sitofp.ll'
+  source_filename = "sitofp.c"
+  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local float @int8_to_float(i8 signext %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i8 %a to float
+    ret float %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local float @int16_to_float(i16 signext %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i16 %a to float
+    ret float %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local float @int32_to_float(i32 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i32 %a to float
+    ret float %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local float @int64_to_float(i64 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i64 %a to float
+    ret float %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local double @int8_to_double(i8 signext %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i8 %a to double
+    ret double %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local double @int16_to_double(i16 signext %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i16 %a to double
+    ret double %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local double @int32_to_double(i32 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i32 %a to double
+    ret double %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local double @int64_to_double(i64 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i64 %a to double
+    ret double %conv
+  }
+
+  attributes #0 = { norecurse nounwind readnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+  !llvm.module.flags = !{!0}
+  !llvm.ident = !{!1}
+
+  !0 = !{i32 1, !"wchar_size", i32 4}
+  !1 = !{!"clang version 7.0.0 (http://llvm.org/git/clang.git a05f37359b23be7c068e19968c8f106edf6f2b34) (http://llvm.org/git/llvm.git d693de1fee74d455e20f96006aac50317ca1da6b)"}
+
+...
+---
+name:            int8_to_float
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+  - { id: 3, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int8_to_float
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $edi
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 24
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[COPY]](s32)
+    ; CHECK: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[COPY1]], [[C]]
+    ; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[SHL]], [[C]]
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s32) = G_SITOFP [[ASHR]](s32)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %1:_(s32) = COPY $edi
+    %0:_(s8) = G_TRUNC %1(s32)
+    %2:_(s32) = G_SITOFP %0(s8)
+    %3:_(s128) = G_ANYEXT %2(s32)
+    $xmm0 = COPY %3(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int16_to_float
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+  - { id: 3, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int16_to_float
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $edi
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[COPY]](s32)
+    ; CHECK: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[COPY1]], [[C]]
+    ; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[SHL]], [[C]]
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s32) = G_SITOFP [[ASHR]](s32)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %1:_(s32) = COPY $edi
+    %0:_(s16) = G_TRUNC %1(s32)
+    %2:_(s32) = G_SITOFP %0(s16)
+    %3:_(s128) = G_ANYEXT %2(s32)
+    $xmm0 = COPY %3(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int32_to_float
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int32_to_float
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $edi
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s32) = G_SITOFP [[COPY]](s32)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %0:_(s32) = COPY $edi
+    %1:_(s32) = G_SITOFP %0(s32)
+    %2:_(s128) = G_ANYEXT %1(s32)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int64_to_float
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $rdi
+
+    ; CHECK-LABEL: name: int64_to_float
+    ; CHECK: liveins: $rdi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $rdi
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s32) = G_SITOFP [[COPY]](s64)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s32)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %0:_(s64) = COPY $rdi
+    %1:_(s32) = G_SITOFP %0(s64)
+    %2:_(s128) = G_ANYEXT %1(s32)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int8_to_double
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+  - { id: 3, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int8_to_double
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $edi
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 24
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[COPY]](s32)
+    ; CHECK: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[COPY1]], [[C]]
+    ; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[SHL]], [[C]]
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s64) = G_SITOFP [[ASHR]](s32)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %1:_(s32) = COPY $edi
+    %0:_(s8) = G_TRUNC %1(s32)
+    %2:_(s64) = G_SITOFP %0(s8)
+    %3:_(s128) = G_ANYEXT %2(s64)
+    $xmm0 = COPY %3(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int16_to_double
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+  - { id: 3, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int16_to_double
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $edi
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[COPY]](s32)
+    ; CHECK: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[COPY1]], [[C]]
+    ; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[SHL]], [[C]]
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s64) = G_SITOFP [[ASHR]](s32)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %1:_(s32) = COPY $edi
+    %0:_(s16) = G_TRUNC %1(s32)
+    %2:_(s64) = G_SITOFP %0(s16)
+    %3:_(s128) = G_ANYEXT %2(s64)
+    $xmm0 = COPY %3(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int32_to_double
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int32_to_double
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $edi
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s64) = G_SITOFP [[COPY]](s32)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %0:_(s32) = COPY $edi
+    %1:_(s64) = G_SITOFP %0(s32)
+    %2:_(s128) = G_ANYEXT %1(s64)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int64_to_double
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.1.entry:
+    liveins: $rdi
+
+    ; CHECK-LABEL: name: int64_to_double
+    ; CHECK: liveins: $rdi
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $rdi
+    ; CHECK: [[SITOFP:%[0-9]+]]:_(s64) = G_SITOFP [[COPY]](s64)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s128) = G_ANYEXT [[SITOFP]](s64)
+    ; CHECK: $xmm0 = COPY [[ANYEXT]](s128)
+    ; CHECK: RET 0, implicit $xmm0
+    %0:_(s64) = COPY $rdi
+    %1:_(s64) = G_SITOFP %0(s64)
+    %2:_(s128) = G_ANYEXT %1(s64)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
Index: test/CodeGen/X86/GlobalISel/x86_64-select-sitofp.mir
===================================================================
--- /dev/null
+++ test/CodeGen/X86/GlobalISel/x86_64-select-sitofp.mir
@@ -0,0 +1,158 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=x86_64-linux-gnu -global-isel -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s
+
+--- |
+  ; ModuleID = 'sitofp_legal.ll'
+  source_filename = "sitofp.c"
+  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local float @int32_to_float(i32 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i32 %a to float
+    ret float %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local float @int64_to_float(i64 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i64 %a to float
+    ret float %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local double @int32_to_double(i32 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i32 %a to double
+    ret double %conv
+  }
+
+  ; Function Attrs: norecurse nounwind readnone uwtable
+  define dso_local double @int64_to_double(i64 %a) local_unnamed_addr #0 {
+  entry:
+    %conv = sitofp i64 %a to double
+    ret double %conv
+  }
+
+  attributes #0 = { norecurse nounwind readnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+  !llvm.module.flags = !{!0}
+  !llvm.ident = !{!1}
+
+  !0 = !{i32 1, !"wchar_size", i32 4}
+  !1 = !{!"clang version 7.0.0 (http://llvm.org/git/clang.git a05f37359b23be7c068e19968c8f106edf6f2b34) (http://llvm.org/git/llvm.git d693de1fee74d455e20f96006aac50317ca1da6b)"}
+
+...
+---
+name:            int32_to_float
+alignment:       4
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gpr }
+  - { id: 1, class: vecr }
+  - { id: 2, class: vecr }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int32_to_float
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:gr32 = COPY $edi
+    ; CHECK: [[CVTSI2SSrr:%[0-9]+]]:fr32 = CVTSI2SSrr [[COPY]]
+    ; CHECK: [[COPY1:%[0-9]+]]:vr128 = COPY [[CVTSI2SSrr]]
+    ; CHECK: $xmm0 = COPY [[COPY1]]
+    ; CHECK: RET 0, implicit $xmm0
+    %0:gpr(s32) = COPY $edi
+    %1:vecr(s32) = G_SITOFP %0(s32)
+    %2:vecr(s128) = G_ANYEXT %1(s32)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int64_to_float
+alignment:       4
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gpr }
+  - { id: 1, class: vecr }
+  - { id: 2, class: vecr }
+body:             |
+  bb.1.entry:
+    liveins: $rdi
+
+    ; CHECK-LABEL: name: int64_to_float
+    ; CHECK: liveins: $rdi
+    ; CHECK: [[COPY:%[0-9]+]]:gr64 = COPY $rdi
+    ; CHECK: [[CVTSI642SSrr:%[0-9]+]]:fr32 = CVTSI642SSrr [[COPY]]
+    ; CHECK: [[COPY1:%[0-9]+]]:vr128 = COPY [[CVTSI642SSrr]]
+    ; CHECK: $xmm0 = COPY [[COPY1]]
+    ; CHECK: RET 0, implicit $xmm0
+    %0:gpr(s64) = COPY $rdi
+    %1:vecr(s32) = G_SITOFP %0(s64)
+    %2:vecr(s128) = G_ANYEXT %1(s32)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int32_to_double
+alignment:       4
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gpr }
+  - { id: 1, class: vecr }
+  - { id: 2, class: vecr }
+body:             |
+  bb.1.entry:
+    liveins: $edi
+
+    ; CHECK-LABEL: name: int32_to_double
+    ; CHECK: liveins: $edi
+    ; CHECK: [[COPY:%[0-9]+]]:gr32 = COPY $edi
+    ; CHECK: [[CVTSI2SDrr:%[0-9]+]]:fr64 = CVTSI2SDrr [[COPY]]
+    ; CHECK: [[COPY1:%[0-9]+]]:vr128 = COPY [[CVTSI2SDrr]]
+    ; CHECK: $xmm0 = COPY [[COPY1]]
+    ; CHECK: RET 0, implicit $xmm0
+    %0:gpr(s32) = COPY $edi
+    %1:vecr(s64) = G_SITOFP %0(s32)
+    %2:vecr(s128) = G_ANYEXT %1(s64)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...
+---
+name:            int64_to_double
+alignment:       4
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gpr }
+  - { id: 1, class: vecr }
+  - { id: 2, class: vecr }
+body:             |
+  bb.1.entry:
+    liveins: $rdi
+
+    ; CHECK-LABEL: name: int64_to_double
+    ; CHECK: liveins: $rdi
+    ; CHECK: [[COPY:%[0-9]+]]:gr64 = COPY $rdi
+    ; CHECK: [[CVTSI642SDrr:%[0-9]+]]:fr64 = CVTSI642SDrr [[COPY]]
+    ; CHECK: [[COPY1:%[0-9]+]]:vr128 = COPY [[CVTSI642SDrr]]
+    ; CHECK: $xmm0 = COPY [[COPY1]]
+    ; CHECK: RET 0, implicit $xmm0
+    %0:gpr(s64) = COPY $rdi
+    %1:vecr(s64) = G_SITOFP %0(s64)
+    %2:vecr(s128) = G_ANYEXT %1(s64)
+    $xmm0 = COPY %2(s128)
+    RET 0, implicit $xmm0
+
+...