Index: llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -247,6 +247,11 @@
     Res = NPN;
     break;
   }
+  case Instruction::FPToUI:
+  case Instruction::FPToSI:
+    Res = CastInst::Create(
+      static_cast<Instruction::CastOps>(Opc), I->getOperand(0), Ty);
+    break;
   default:
     // TODO: Can handle more cases here.
     llvm_unreachable("Unreachable!");
@@ -491,6 +496,15 @@
         return false;
     return true;
   }
+  case Instruction::FPToUI:
+  case Instruction::FPToSI: {
+    Type *InputTy = I->getOperand(0)->getType()->getScalarType();
+    uint32_t BitWidth = Ty->getScalarSizeInBits();
+    uint32_t MinBitWidth = InputTy->getScalarSizeInBits() + 1;
+    if (InputTy->isHalfTy() && I->getOpcode() == Instruction::FPToUI)
+      MinBitWidth = 16;
+    return BitWidth >= MinBitWidth;
+  }
   default:
     // TODO: Can handle more cases here.
     break;
Index: llvm/test/Transforms/InstCombine/trunc-fp-to-int.ll
===================================================================
--- llvm/test/Transforms/InstCombine/trunc-fp-to-int.ll
+++ llvm/test/Transforms/InstCombine/trunc-fp-to-int.ll
@@ -27,9 +27,8 @@
 
 define i16 @half_fptoui_i17_i16(half %x) {
 ; CHECK-LABEL: @half_fptoui_i17_i16(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i17
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i17 [[CONV]] to i16
-; CHECK-NEXT:    ret i16 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i16
+; CHECK-NEXT:    ret i16 [[CONV]]
 ;
   %conv = fptoui half %x to i17
   %conv.1 = trunc i17 %conv to i16
@@ -38,9 +37,8 @@
 
 define i16 @half_fptoui_i17_i16_noundef(half noundef %x) {
 ; CHECK-LABEL: @half_fptoui_i17_i16_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i17
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i17 [[CONV]] to i16
-; CHECK-NEXT:    ret i16 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i16
+; CHECK-NEXT:    ret i16 [[CONV]]
 ;
   %conv = fptoui half %x to i17
   %conv.1 = trunc i17 %conv to i16
@@ -49,9 +47,8 @@
 
 define i16 @half_fptoui_i32_i16(half %x) {
 ; CHECK-LABEL: @half_fptoui_i32_i16(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i32
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i32 [[CONV]] to i16
-; CHECK-NEXT:    ret i16 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i16
+; CHECK-NEXT:    ret i16 [[CONV]]
 ;
   %conv = fptoui half %x to i32
   %conv.1 = trunc i32 %conv to i16
@@ -60,9 +57,8 @@
 
 define i16 @half_fptoui_i32_i16_noundef(half noundef %x) {
 ; CHECK-LABEL: @half_fptoui_i32_i16_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i32
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i32 [[CONV]] to i16
-; CHECK-NEXT:    ret i16 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui half [[X:%.*]] to i16
+; CHECK-NEXT:    ret i16 [[CONV]]
 ;
   %conv = fptoui half %x to i32
   %conv.1 = trunc i32 %conv to i16
@@ -95,9 +91,8 @@
 
 define <4 x i16> @half_fptoui_4xi32_4xi16(<4 x half> %x) {
 ; CHECK-LABEL: @half_fptoui_4xi32_4xi16(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui <4 x half> [[X:%.*]] to <4 x i32>
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc <4 x i32> [[CONV]] to <4 x i16>
-; CHECK-NEXT:    ret <4 x i16> [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui <4 x half> [[X:%.*]] to <4 x i16>
+; CHECK-NEXT:    ret <4 x i16> [[CONV]]
 ;
   %conv = fptoui <4 x half> %x to <4 x i32>
   %conv.1 = trunc <4 x i32> %conv to <4 x i16>
@@ -106,9 +101,8 @@
 
 define <4 x i16> @half_fptoui_4xi32_4xi16_noundef(<4 x half> noundef %x) {
 ; CHECK-LABEL: @half_fptoui_4xi32_4xi16_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui <4 x half> [[X:%.*]] to <4 x i32>
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc <4 x i32> [[CONV]] to <4 x i16>
-; CHECK-NEXT:    ret <4 x i16> [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui <4 x half> [[X:%.*]] to <4 x i16>
+; CHECK-NEXT:    ret <4 x i16> [[CONV]]
 ;
   %conv = fptoui <4 x half> %x to <4 x i32>
   %conv.1 = trunc <4 x i32> %conv to <4 x i16>
@@ -118,8 +112,8 @@
 ; Negative test.
 define i31 @float_fptoui_i64_i31(float %x) {
 ; CHECK-LABEL: @float_fptoui_i64_i31(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i31
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i62
+; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i62 [[CONV]] to i31
 ; CHECK-NEXT:    ret i31 [[CONV_1]]
 ;
   %conv = fptoui float %x to i64
@@ -130,8 +124,8 @@
 ; Negative test.
 define i31 @float_fptoui_i64_i31_noundef(float noundef %x) {
 ; CHECK-LABEL: @float_fptoui_i64_i31_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i31
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i62
+; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i62 [[CONV]] to i31
 ; CHECK-NEXT:    ret i31 [[CONV_1]]
 ;
   %conv = fptoui float %x to i64
@@ -165,9 +159,8 @@
 
 define i33 @float_fptoui_i64_i33(float %x) {
 ; CHECK-LABEL: @float_fptoui_i64_i33(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i33
-; CHECK-NEXT:    ret i33 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i33
+; CHECK-NEXT:    ret i33 [[CONV]]
 ;
   %conv = fptoui float %x to i64
   %conv.1 = trunc i64 %conv to i33
@@ -176,9 +169,8 @@
 
 define i33 @float_fptoui_i64_i33_noundef(float noundef %x) {
 ; CHECK-LABEL: @float_fptoui_i64_i33_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i33
-; CHECK-NEXT:    ret i33 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i33
+; CHECK-NEXT:    ret i33 [[CONV]]
 ;
   %conv = fptoui float %x to i64
   %conv.1 = trunc i64 %conv to i33
@@ -187,9 +179,8 @@
 
 define i64 @float_fptoui_i128_i64(float %x) {
 ; CHECK-LABEL: @float_fptoui_i128_i64(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i128
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i128 [[CONV]] to i64
-; CHECK-NEXT:    ret i64 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i64
+; CHECK-NEXT:    ret i64 [[CONV]]
 ;
   %conv = fptoui float %x to i128
   %conv.1 = trunc i128 %conv to i64
@@ -198,9 +189,8 @@
 
 define i64 @float_fptoui_i128_i64_noundef(float noundef %x) {
 ; CHECK-LABEL: @float_fptoui_i128_i64_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i128
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i128 [[CONV]] to i64
-; CHECK-NEXT:    ret i64 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptoui float [[X:%.*]] to i64
+; CHECK-NEXT:    ret i64 [[CONV]]
 ;
   %conv = fptoui float %x to i128
   %conv.1 = trunc i128 %conv to i64
@@ -305,9 +295,8 @@
 
 define <4 x i32> @half_fptosi_4xi64_4xi32(<4 x half> %x) {
 ; CHECK-LABEL: @half_fptosi_4xi64_4xi32(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi <4 x half> [[X:%.*]] to <4 x i64>
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc <4 x i64> [[CONV]] to <4 x i32>
-; CHECK-NEXT:    ret <4 x i32> [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi <4 x half> [[X:%.*]] to <4 x i32>
+; CHECK-NEXT:    ret <4 x i32> [[CONV]]
 ;
   %conv = fptosi <4 x half> %x to <4 x i64>
   %conv.1 = trunc <4 x i64> %conv to <4 x i32>
@@ -317,8 +306,8 @@
 ; Negative test.
 define i31 @float_fptosi_i64_i31(float %x) {
 ; CHECK-LABEL: @float_fptosi_i64_i31(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i31
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i62
+; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i62 [[CONV]] to i31
 ; CHECK-NEXT:    ret i31 [[CONV_1]]
 ;
   %conv = fptosi float %x to i64
@@ -329,8 +318,8 @@
 ; Negative test.
 define i31 @float_fptosi_i64_i31_noundef(float noundef %x) {
 ; CHECK-LABEL: @float_fptosi_i64_i31_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i31
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i62
+; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i62 [[CONV]] to i31
 ; CHECK-NEXT:    ret i31 [[CONV_1]]
 ;
   %conv = fptosi float %x to i64
@@ -364,9 +353,8 @@
 
 define i33 @float_fptosi_i64_i33(float %x) {
 ; CHECK-LABEL: @float_fptosi_i64_i33(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i33
-; CHECK-NEXT:    ret i33 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i33
+; CHECK-NEXT:    ret i33 [[CONV]]
 ;
   %conv = fptosi float %x to i64
   %conv.1 = trunc i64 %conv to i33
@@ -375,9 +363,8 @@
 
 define i33 @float_fptosi_i64_i33_noundef(float noundef %x) {
 ; CHECK-LABEL: @float_fptosi_i64_i33_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i64
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i64 [[CONV]] to i33
-; CHECK-NEXT:    ret i33 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i33
+; CHECK-NEXT:    ret i33 [[CONV]]
 ;
   %conv = fptosi float %x to i64
   %conv.1 = trunc i64 %conv to i33
@@ -386,9 +373,8 @@
 
 define i64 @float_fptosi_i128_i64(float %x) {
 ; CHECK-LABEL: @float_fptosi_i128_i64(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i128
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i128 [[CONV]] to i64
-; CHECK-NEXT:    ret i64 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i64
+; CHECK-NEXT:    ret i64 [[CONV]]
 ;
   %conv = fptosi float %x to i128
   %conv.1 = trunc i128 %conv to i64
@@ -397,9 +383,8 @@
 
 define i64 @float_fptosi_i128_i64_noundef(float noundef %x) {
 ; CHECK-LABEL: @float_fptosi_i128_i64_noundef(
-; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i128
-; CHECK-NEXT:    [[CONV_1:%.*]] = trunc i128 [[CONV]] to i64
-; CHECK-NEXT:    ret i64 [[CONV_1]]
+; CHECK-NEXT:    [[CONV:%.*]] = fptosi float [[X:%.*]] to i64
+; CHECK-NEXT:    ret i64 [[CONV]]
 ;
   %conv = fptosi float %x to i128
   %conv.1 = trunc i128 %conv to i64