Index: llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.h
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.h
+++ llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.h
@@ -146,6 +146,9 @@
   bool selectSMFMACIntrin(MachineInstr &I) const;
   bool selectWaveAddress(MachineInstr &I) const;
 
+  std::pair<Register, unsigned> getVOP3ModsImpl(MachineOperand &Root,
+                                                bool AllowAbs = true,
+                                                bool OpSel = false) const;
   std::pair<Register, unsigned>
   selectVOP3ModsImpl(MachineOperand &Root, bool AllowAbs = true,
                      bool OpSel = false, bool ForceVGPR = false) const;
Index: llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
@@ -3386,10 +3386,10 @@
 
 }
 
-std::pair<Register, unsigned> AMDGPUInstructionSelector::selectVOP3ModsImpl(
-    MachineOperand &Root, bool AllowAbs, bool OpSel, bool ForceVGPR) const {
+std::pair<Register, unsigned>
+AMDGPUInstructionSelector::getVOP3ModsImpl(MachineOperand &Root, bool AllowAbs,
+                                           bool OpSel) const {
   Register Src = Root.getReg();
-  Register OrigSrc = Src;
   unsigned Mods = 0;
   MachineInstr *MI = getDefIgnoringCopies(Src, *MRI);
 
@@ -3407,6 +3407,16 @@
   if (OpSel)
     Mods |= SISrcMods::OP_SEL_0;
 
+  return std::make_pair(Src, Mods);
+}
+
+std::pair<Register, unsigned> AMDGPUInstructionSelector::selectVOP3ModsImpl(
+    MachineOperand &Root, bool AllowAbs, bool OpSel, bool ForceVGPR) const {
+  Register OrigSrc = Root.getReg();
+  Register Src;
+  unsigned Mods;
+  std::tie(Src, Mods) = getVOP3ModsImpl(Root, AllowAbs, OpSel);
+
   if ((Mods != 0 || ForceVGPR) &&
       RBI.getRegBank(Src, *MRI, TRI)->getID() != AMDGPU::VGPRRegBankID) {
     MachineInstr *UseMI = Root.getParent();
@@ -3417,7 +3427,7 @@
     Register VGPRSrc = MRI->cloneVirtualRegister(OrigSrc);
     BuildMI(*UseMI->getParent(), UseMI, UseMI->getDebugLoc(),
             TII.get(AMDGPU::COPY), VGPRSrc)
-      .addReg(Src);
+        .addReg(Src);
     Src = VGPRSrc;
   }
 
@@ -4798,10 +4808,14 @@
 
   Register Src;
   unsigned Mods;
-  std::tie(Src, Mods) = selectVOP3ModsImpl(Root);
+  std::tie(Src, Mods) = getVOP3ModsImpl(Root);
 
   MachineInstr *MI = getDefIgnoringCopies(Src, *MRI);
   if (MI->getOpcode() == AMDGPU::G_FPEXT) {
+    // selectVOP3ModsImpl can create copy, make sure that select will succeed
+    // to avoid creating dead copy instruction.
+    std::tie(Src, Mods) = selectVOP3ModsImpl(Root);
+    MachineInstr *MI = getDefIgnoringCopies(Src, *MRI);
     MachineOperand *MO = &MI->getOperand(1);
     Src = MO->getReg();
     MI = getDefIgnoringCopies(Src, *MRI);
Index: llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fma-add-mul.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fma-add-mul.ll
+++ llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fma-add-mul.ll
@@ -128,6 +128,55 @@
   ret float %b
 }
 
+define amdgpu_ps float @dont_crash_after_fma_mix_select_attempt(float inreg %x, float %y, float %z) {
+; GFX9-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX9:       ; %bb.0: ; %.entry
+; GFX9-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX9-NEXT:    ; return to shader part epilog
+;
+; GFX9-CONTRACT-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX9-CONTRACT:       ; %bb.0: ; %.entry
+; GFX9-CONTRACT-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX9-CONTRACT-NEXT:    ; return to shader part epilog
+;
+; GFX9-DENORM-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX9-DENORM:       ; %bb.0: ; %.entry
+; GFX9-DENORM-NEXT:    v_mad_f32 v0, |s0|, v0, v1
+; GFX9-DENORM-NEXT:    ; return to shader part epilog
+;
+; GFX9-UNSAFE-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX9-UNSAFE:       ; %bb.0: ; %.entry
+; GFX9-UNSAFE-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX9-UNSAFE-NEXT:    ; return to shader part epilog
+;
+; GFX10-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX10:       ; %bb.0: ; %.entry
+; GFX10-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX10-NEXT:    ; return to shader part epilog
+;
+; GFX10-CONTRACT-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX10-CONTRACT:       ; %bb.0: ; %.entry
+; GFX10-CONTRACT-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX10-CONTRACT-NEXT:    ; return to shader part epilog
+;
+; GFX10-DENORM-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX10-DENORM:       ; %bb.0: ; %.entry
+; GFX10-DENORM-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX10-DENORM-NEXT:    ; return to shader part epilog
+;
+; GFX10-UNSAFE-LABEL: dont_crash_after_fma_mix_select_attempt:
+; GFX10-UNSAFE:       ; %bb.0: ; %.entry
+; GFX10-UNSAFE-NEXT:    v_fma_f32 v0, |s0|, v0, v1
+; GFX10-UNSAFE-NEXT:    ; return to shader part epilog
+.entry:
+  %abs_x = call contract float @llvm.fabs.f32(float %x)
+  %a = fmul contract float %abs_x, %y
+  %b = fadd contract float %a, %z
+  ret float %b
+}
+
+declare float @llvm.fabs.f32(float)
+
 define float @test_add_mul_multiple_defs_z(float %x, float %y, <2 x float> addrspace(1)* %vec_ptr) {
 ; GFX9-LABEL: test_add_mul_multiple_defs_z:
 ; GFX9:       ; %bb.0: ; %.entry