diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -4551,8 +4551,10 @@
     // doesn't happen.
     LHSPtrAdd->moveBefore(&MI);
     Register RHSReg = MI.getOffsetReg();
+    // set VReg will cause type mismatch if it comes from extend/trunc
+    auto NewCst = B.buildConstant(MRI.getType(RHSReg), LHSCstOff->Value);
     Observer.changingInstr(MI);
-    MI.getOperand(2).setReg(LHSCstOff->VReg);
+    MI.getOperand(2).setReg(NewCst.getReg(0));
     Observer.changedInstr(MI);
     Observer.changingInstr(*LHSPtrAdd);
     LHSPtrAdd->getOperand(2).setReg(RHSReg);
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-ptradd-chain.mir b/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-ptradd-chain.mir
--- a/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-ptradd-chain.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-ptradd-chain.mir
@@ -1,5 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: llc -mtriple aarch64-apple-ios  -run-pass=aarch64-prelegalizer-combiner --aarch64prelegalizercombinerhelper-only-enable-rule="ptr_add_immed_chain"  %s -o - -verify-machineinstrs | FileCheck %s
+# RUN: llc -mtriple aarch64-apple-ios  -run-pass=aarch64-prelegalizer-combiner  %s -o - -verify-machineinstrs | FileCheck %s
 # REQUIRES: asserts
 
 # Check that we fold two adds of constant offsets with G_PTR_ADD into a single G_PTR_ADD.
@@ -105,3 +105,32 @@
     $x1 = COPY %ld_other(s64)
     RET_ReallyLR implicit $x0
 ...
+---
+# PR58906
+name: ptradd_constant_type_mismatch
+tracksRegLiveness: true
+body:             |
+  bb.1:
+    liveins: $x0, $x1
+
+    ; CHECK-LABEL: name: ptradd_constant_type_mismatch
+    ; CHECK: liveins: $x0, $x1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(p0) = COPY $x0
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s64) = COPY $x1
+    ; CHECK-NEXT: [[PTR_ADD:%[0-9]+]]:_(p0) = G_PTR_ADD [[COPY]], [[COPY1]](s64)
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 8
+    ; CHECK-NEXT: [[PTR_ADD1:%[0-9]+]]:_(p0) = G_PTR_ADD [[PTR_ADD]], [[C]](s64)
+    ; CHECK-NEXT: %ld:_(s64) = G_LOAD [[PTR_ADD1]](p0) :: (load (s64))
+    ; CHECK-NEXT: $x0 = COPY %ld(s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(p0) = COPY $x0
+    %1:_(s64) = COPY $x1
+    %2:_(s32) = G_CONSTANT i32 8
+    %3:_(s64) = G_ZEXT %2:_(s32)
+    %4:_(p0) = G_PTR_ADD %0:_, %3:_(s64)
+    %5:_(p0) = G_PTR_ADD %4:_, %1:_(s64)
+    %ld:_(s64) = G_LOAD %5(p0) :: (load 8)
+    $x0 = COPY %ld(s64)
+    RET_ReallyLR implicit $x0
+...