Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -17916,6 +17916,7 @@
   if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Value)) {
     if (Ld->getBasePtr() == Ptr && ST->getMemoryVT() == Ld->getMemoryVT() &&
         ST->isUnindexed() && ST->isSimple() &&
+        Ld->getAddressSpace() == ST->getAddressSpace() &&
         // There can't be any side effects between the load and store, such as
         // a call or store.
         Chain.reachesChainWithoutSideEffects(SDValue(Ld, 1))) {
@@ -17929,7 +17930,8 @@
     if (ST->isUnindexed() && ST->isSimple() &&
         ST1->isUnindexed() && ST1->isSimple()) {
       if (ST1->getBasePtr() == Ptr && ST1->getValue() == Value &&
-          ST->getMemoryVT() == ST1->getMemoryVT()) {
+          ST->getMemoryVT() == ST1->getMemoryVT() &&
+          ST->getAddressSpace() == ST1->getAddressSpace()) {
         // If this is a store followed by a store with the same value to the
         // same location, then the store is dead/noop.
         return Chain;
@@ -17940,7 +17942,8 @@
           // BaseIndexOffset and the code below requires knowing the size
           // of a vector, so bail out if MemoryVT is scalable.
           !ST->getMemoryVT().isScalableVector() &&
-          !ST1->getMemoryVT().isScalableVector()) {
+          !ST1->getMemoryVT().isScalableVector() &&
+          ST->getAddressSpace() == ST1->getAddressSpace()) {
         const BaseIndexOffset STBase = BaseIndexOffset::match(ST, DAG);
         const BaseIndexOffset ChainBase = BaseIndexOffset::match(ST1, DAG);
         unsigned STBitSize = ST->getMemoryVT().getFixedSizeInBits();
Index: llvm/test/CodeGen/X86/dagcombine-dead-store.ll
===================================================================
--- llvm/test/CodeGen/X86/dagcombine-dead-store.ll
+++ llvm/test/CodeGen/X86/dagcombine-dead-store.ll
@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc < %s -mtriple=i686-pc-linux | FileCheck %s
 
 ; Checks that the stores aren't eliminated by the DAG combiner, because the address
@@ -5,63 +6,64 @@
 ; The test's 'same' and 'diff' notation depicts the pointer value exposing bugs hitting
 ; corner cases where the case where the pointer value is either the same, or different.
 
-; FIXME: DAG combine incorrectly eliminates store if pointer is of same value.
-
-; CHECK-LABEL: copy_fs_same:
-; CHECK: # %bb.0:
-; CHECK-NEXT: movl 1, %eax
-; CHECK-NEXT: retl
 define i32 @copy_fs_same() {
+; CHECK-LABEL: copy_fs_same:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl 1, %eax
+; CHECK-NEXT:    movl %eax, %fs:1
+; CHECK-NEXT:    retl
 entry:
    %0 = load i32, i32* inttoptr (i64 1 to i32*), align 4
   store i32 %0, i32 addrspace(257)* inttoptr (i64 1 to i32 addrspace(257)*), align 4
   ret i32 %0
 }
 
-; CHECK-LABEL: copy_fs_diff:
-; CHECK: # %bb.0:
-; CHECK-NEXT: movl 1, %eax
-; CHECK-NEXT: movl %eax, %fs:2
-; CHECK-NEXT: retl
 define i32 @copy_fs_diff() {
+; CHECK-LABEL: copy_fs_diff:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl 1, %eax
+; CHECK-NEXT:    movl %eax, %fs:2
+; CHECK-NEXT:    retl
 entry:
    %0 = load i32, i32* inttoptr (i64 1 to i32*), align 4
   store i32 %0, i32 addrspace(257)* inttoptr (i64 2 to i32 addrspace(257)*), align 4
   ret i32 %0
 }
 
-; CHECK-LABEL: output_fs_same:
-; CHECK: # %bb.0:
-; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
-; CHECK-NEXT: movl %eax, 1
-; CHECK-NEXT: retl
 define void @output_fs_same(i32 %v) {
+; CHECK-LABEL: output_fs_same:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl %eax, 1
+; CHECK-NEXT:    movl %eax, %fs:1
+; CHECK-NEXT:    retl
 entry:
   store i32 %v, i32* inttoptr (i64 1 to i32*), align 4
   store i32 %v, i32 addrspace(257)* inttoptr (i64 1 to i32 addrspace(257)*), align 4
   ret void
 }
 
-; CHECK-LABEL: output_fs_diff:
-; CHECK: # %bb.0:
-; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
-; CHECK-NEXT: movl %eax, 1
-; CHECK-NEXT: movl %eax, %fs:2
-; CHECK-NEXT: retl
 define void @output_fs_diff(i32 %v) {
+; CHECK-LABEL: output_fs_diff:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl %eax, 1
+; CHECK-NEXT:    movl %eax, %fs:2
+; CHECK-NEXT:    retl
 entry:
   store i32 %v, i32* inttoptr (i64 1 to i32*), align 4
   store i32 %v, i32 addrspace(257)* inttoptr (i64 2 to i32 addrspace(257)*), align 4
   ret void
 }
 
-; CHECK-LABEL: output_indexed_fs_same:
-; CHECK: # %bb.0:
-; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
-; CHECK-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; CHECK-NEXT: movl %eax, 168(%ecx)
-; CHECK-NEXT: retl
 define void @output_indexed_fs_same(i32 %v, i32* %b) {
+; CHECK-LABEL: output_indexed_fs_same:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; CHECK-NEXT:    movl %eax, 168(%ecx)
+; CHECK-NEXT:    movl %eax, %fs:168(%ecx)
+; CHECK-NEXT:    retl
   %p = getelementptr i32, i32* %b, i64 42
   %pa = addrspacecast i32* %p to i32 addrspace(257)*
   store i32 %v, i32* %p, align 4
@@ -69,14 +71,14 @@
   ret void
 }
 
-; CHECK-LABEL: output_indexed_fs_diff:
-; CHECK: # %bb.0:
-; CHECK-NEXT: movl {{[0-9]+}}(%esp), %eax
-; CHECK-NEXT: movl {{[0-9]+}}(%esp), %ecx
-; CHECK-NEXT: movl %eax, 168(%ecx)
-; CHECK-NEXT: movl %eax, %fs:184(%ecx)
-; CHECK-NEXT: retl
 define void @output_indexed_fs_diff(i32 %v, i32* %b) {
+; CHECK-LABEL: output_indexed_fs_diff:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; CHECK-NEXT:    movl %eax, 168(%ecx)
+; CHECK-NEXT:    movl %eax, %fs:184(%ecx)
+; CHECK-NEXT:    retl
   %p = getelementptr i32, i32* %b, i64 42
   %pa = addrspacecast i32* %p to i32 addrspace(257)*
   %pad = getelementptr i32, i32 addrspace(257)* %pa, i64 4