[SDAG] Ensure load is included in output chain of sincos expansion

The load not being included in the chain meant that it could materialize
after a `@llvm.lifetime.end` annotation on the pointer. This could
result in miscompiles if the stack slot is reused for another value.

Fixes #140491

Author: MacDue

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -2625,16 +2625,19 @@ bool SelectionDAG::expandMultipleResultFPLibCall(
       continue;
     }
     MachinePointerInfo PtrInfo;
+    SDValue LoadResult =
+        getLoad(Node->getValueType(ResNo), DL, CallChain, ResultPtr, PtrInfo);
+    SDValue OutChain = LoadResult.getValue(1);
+
     if (StoreSDNode *ST = ResultStores[ResNo]) {
       // Replace store with the library call.
-      ReplaceAllUsesOfValueWith(SDValue(ST, 0), CallChain);
+      ReplaceAllUsesOfValueWith(SDValue(ST, 0), OutChain);
       PtrInfo = ST->getPointerInfo();
     } else {
       PtrInfo = MachinePointerInfo::getFixedStack(
           getMachineFunction(), cast<FrameIndexSDNode>(ResultPtr)->getIndex());
     }
-    SDValue LoadResult =
-        getLoad(Node->getValueType(ResNo), DL, CallChain, ResultPtr, PtrInfo);
+
     Results.push_back(LoadResult);
   }
 

llvm/test/CodeGen/X86/sincos-lifetimes-issue-140491.ll

@@ -10,27 +10,29 @@ define hidden noundef i32 @sincos_stack_slot_with_lifetime(float %in) local_unna
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:    pushq %rbx
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
-; CHECK-NEXT:    subq $16, %rsp
-; CHECK-NEXT:    .cfi_def_cfa_offset 32
+; CHECK-NEXT:    subq $32, %rsp
+; CHECK-NEXT:    .cfi_def_cfa_offset 48
 ; CHECK-NEXT:    .cfi_offset %rbx, -16
 ; CHECK-NEXT:    leaq 12(%rsp), %rdi
 ; CHECK-NEXT:    leaq 8(%rsp), %rbx
 ; CHECK-NEXT:    movq %rbx, %rsi
 ; CHECK-NEXT:    callq sincosf@PLT
+; CHECK-NEXT:    movss 8(%rsp), %xmm0 # xmm0 = mem[0],zero,zero,zero
+; CHECK-NEXT:    movaps %xmm0, 16(%rsp) # 16-byte Spill
 ; CHECK-NEXT:    movq %rbx, %rdi
 ; CHECK-NEXT:    callq use_ptr
 ; CHECK-NEXT:    movss 12(%rsp), %xmm0 # xmm0 = mem[0],zero,zero,zero
 ; CHECK-NEXT:    xorps {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
 ; CHECK-NEXT:    movss %xmm0, 8(%rsp)
 ; CHECK-NEXT:    leaq 8(%rsp), %rdi
 ; CHECK-NEXT:    callq use_ptr
-; CHECK-NEXT:    movss 8(%rsp), %xmm0 # xmm0 = mem[0],zero,zero,zero
+; CHECK-NEXT:    movaps 16(%rsp), %xmm0 # 16-byte Reload
 ; CHECK-NEXT:    xorps {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
 ; CHECK-NEXT:    movss %xmm0, 8(%rsp)
 ; CHECK-NEXT:    leaq 8(%rsp), %rdi
 ; CHECK-NEXT:    callq use_ptr
 ; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:    addq $16, %rsp
+; CHECK-NEXT:    addq $32, %rsp
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
 ; CHECK-NEXT:    popq %rbx
 ; CHECK-NEXT:    .cfi_def_cfa_offset 8