[FastISel][AArch64] Emit immediate version of icmp (subs) for null pointer check.
This is a minor change to use the immediate version when the operand is a null
value. This should get rid of an unnecessary 'mov' instruction in debug
builds and align the code more with the one generated by SelectionDAG.
This fixes rdar://problem/18785125.
llvm-svn: 220713
diff --git a/llvm/lib/Target/AArch64/AArch64FastISel.cpp b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
index 5527213..01b2dee 100644
--- a/llvm/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
@@ -1084,7 +1084,7 @@
RetVT.SimpleTy = std::max(RetVT.SimpleTy, MVT::i32);
// Canonicalize immediates to the RHS first.
- if (UseAdd && isa<ConstantInt>(LHS) && !isa<ConstantInt>(RHS))
+ if (UseAdd && isa<Constant>(LHS) && !isa<Constant>(RHS))
std::swap(LHS, RHS);
// Canonicalize mul by power of 2 to the RHS.
@@ -1118,7 +1118,11 @@
else
ResultReg = emitAddSub_ri(UseAdd, RetVT, LHSReg, LHSIsKill, Imm, SetFlags,
WantResult);
- }
+ } else if (const auto *C = dyn_cast<Constant>(RHS))
+ if (C->isNullValue())
+ ResultReg = emitAddSub_ri(UseAdd, RetVT, LHSReg, LHSIsKill, 0, SetFlags,
+ WantResult);
+
if (ResultReg)
return ResultReg;
diff --git a/llvm/test/CodeGen/AArch64/arm64-fast-isel-icmp.ll b/llvm/test/CodeGen/AArch64/arm64-fast-isel-icmp.ll
index 2d60783..245c70e 100644
--- a/llvm/test/CodeGen/AArch64/arm64-fast-isel-icmp.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-fast-isel-icmp.ll
@@ -40,6 +40,26 @@
ret i32 %conv
}
+define i32 @icmp_eq_ptr(i8* %a) {
+entry:
+; CHECK-LABEL: icmp_eq_ptr
+; CHECK: cmp x0, #0
+; CHECK-NEXT: cset {{.+}}, eq
+ %cmp = icmp eq i8* %a, null
+ %conv = zext i1 %cmp to i32
+ ret i32 %conv
+}
+
+define i32 @icmp_ne_ptr(i8* %a) {
+entry:
+; CHECK-LABEL: icmp_ne_ptr
+; CHECK: cmp x0, #0
+; CHECK-NEXT: cset {{.+}}, ne
+ %cmp = icmp ne i8* %a, null
+ %conv = zext i1 %cmp to i32
+ ret i32 %conv
+}
+
define i32 @icmp_ugt(i32 %a, i32 %b) nounwind ssp {
entry:
; CHECK-LABEL: icmp_ugt