[DAGCombiner] Push truncate through adde when the carry isn't used.

Summary: As per title.

Reviewers: mkuper, spatel, bkramer, RKSimon, zvi

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29528

llvm-svn: 294394
diff --git a/llvm/test/CodeGen/X86/known-bits.ll b/llvm/test/CodeGen/X86/known-bits.ll
index f3fa127..e458d7ab 100644
--- a/llvm/test/CodeGen/X86/known-bits.ll
+++ b/llvm/test/CodeGen/X86/known-bits.ll
@@ -151,8 +151,7 @@
 ; X64-NEXT:    andq $-1024, %rdi # imm = 0xFC00
 ; X64-NEXT:    andq $-1024, %rsi # imm = 0xFC00
 ; X64-NEXT:    addq %rdi, %rsi
-; X64-NEXT:    sbbq %rax, %rax
-; X64-NEXT:    subl %eax, %edx
+; X64-NEXT:    adcl $0, %edx
 ; X64-NEXT:    shldq $54, %rsi, %rdx
 ; X64-NEXT:    xorl %eax, %eax
 ; X64-NEXT:    retq