diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/knownbits-ptrtoint.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/knownbits-ptrtoint.mir
new file mode 100644
index 0000000000000..4073568fd4210
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/knownbits-ptrtoint.mir
@@ -0,0 +1,110 @@
+# NOTE: Assertions have been autogenerated by utils/update_givaluetracking_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn -passes="print<gisel-value-tracking>" %s -filetype=null 2>&1 | FileCheck %s
+## Check that we don't incorrectly assume known zeroes for and extend of a truncated ptrtoint
+## Test case for https://github.com/llvm/llvm-project/issues/139598
+---
+## We should see 128 unknown bits.
+name:            PtrToInt
+body:             |
+  bb.0:
+  ; CHECK-LABEL: name: @PtrToInt
+  ; CHECK-NEXT: %0:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %1:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %2:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %3:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %4:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %5:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(p8) = G_MERGE_VALUES %0(s32), %1(s32), %2(s32), %3(s32)
+    %5:_(s128) = G_PTRTOINT %4(p8)
+...
+---
+## We should see 128 high zeroes followed by 128 unknown bits for extending ptrtoint.
+name:            PtrToIntExt
+body:             |
+  bb.0:
+  ; CHECK-LABEL: name: @PtrToIntExt
+  ; CHECK-NEXT: %0:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %1:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %2:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %3:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %4:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %5:_ KnownBits:00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:128
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(p8) = G_MERGE_VALUES %0(s32), %1(s32), %2(s32), %3(s32)
+    %5:_(s256) = G_PTRTOINT %4(p8)
+...
+---
+## We should see 48 unknown bits for truncating ptrtoint.
+name:            PtrToIntTrunc
+body:             |
+  bb.0:
+  ; CHECK-LABEL: name: @PtrToIntTrunc
+  ; CHECK-NEXT: %0:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %1:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %2:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %3:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %4:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %5:_ KnownBits:???????????????????????????????????????????????? SignBits:1
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(p8) = G_MERGE_VALUES %0(s32), %1(s32), %2(s32), %3(s32)
+    %5:_(s48) = G_PTRTOINT %4(p8)
+...
+---
+## This is the test for issue 139598: Truncating and then extending the
+## G_PTRTOINT result was filling all bits above the index bitwidth with known
+## zeroes even though the incoming value is completely unknown and G_PTRTOINT.
+## is lowered to a bitwise copy.
+## We should see all zero high bits with 48 unknown bits.
+name:            PtrToIntTruncExplicitExt
+body:             |
+  bb.0:
+  ; CHECK-LABEL: name: @PtrToIntTruncExplicitExt
+  ; CHECK-NEXT: %0:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %1:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %2:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %3:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %4:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %5:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %6:_ KnownBits:???????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %7:_ KnownBits:0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000???????????????????????????????????????????????? SignBits:208
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(p8) = G_MERGE_VALUES %0(s32), %1(s32), %2(s32), %3(s32)
+    %5:_(s128) = G_PTRTOINT %4(p8)
+    %6:_(s48) = G_TRUNC %5(s128)
+    %7:_(s256) = G_ZEXT %6(s48)
+...
+---
+## Same test again but this time have the G_PTRTOINT do the truncation.
+## We should see all zero high bits with 48 unknown bits.
+name:            PtrToIntTruncImplicitExt
+body:             |
+  bb.0:
+  ; CHECK-LABEL: name: @PtrToIntTruncImplicitExt
+  ; CHECK-NEXT: %0:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %1:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %2:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %3:_ KnownBits:???????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %4:_ KnownBits:???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %5:_ KnownBits:???????????????????????????????????????????????? SignBits:1
+  ; CHECK-NEXT: %6:_ KnownBits:0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000???????????????????????????????????????????????? SignBits:208
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(p8) = G_MERGE_VALUES %0(s32), %1(s32), %2(s32), %3(s32)
+    %5:_(s48) = G_PTRTOINT %4(p8)
+    %6:_(s256) = G_ZEXT %5(s48)
+...