Use "test reg,reg" in place of "cmp reg,0" for 64-bit operands. This was

previously only done for 32-bit and smaller operands.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42024 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86InstrX86-64.td b/lib/Target/X86/X86InstrX86-64.td
index 0c02f19198d33814a95f43cc86712b15380f04cc..89d952a5b0523962446c9b02f4a9b18c26af12c7 100644 (file)
--- a/lib/Target/X86/X86InstrX86-64.td
+++ b/lib/Target/X86/X86InstrX86-64.td
@@ -1076,6 +1076,12 @@ def : Pat<(X86tailcall (i64 texternalsym:$dst)),
 def : Pat<(X86tailcall GR64:$dst),
           (CALL64r GR64:$dst)>;
 
+// Comparisons.
+
+// TEST R,R is smaller than CMP R,0
+def : Pat<(X86cmp GR64:$src1, 0),
+          (TEST64rr GR64:$src1, GR64:$src1)>;
+
 // {s|z}extload bool -> {s|z}extload byte
 def : Pat<(sextloadi64i1 addr:$src), (MOVSX64rm8 addr:$src)>;
 def : Pat<(zextloadi64i1 addr:$src), (MOVZX64rm8 addr:$src)>;

diff --git a/test/CodeGen/X86/cmp0.ll b/test/CodeGen/X86/cmp0.ll
new file mode 100644 (file)
index 0000000..f66f90c
--- /dev/null
+++ b/test/CodeGen/X86/cmp0.ll
@@ -0,0 +1,7 @@
+; RUN: llvm-as < %s | llc -march=x86-64 | grep -v cmp
+
+define i64 @foo(i64 %x) {
+  %t = icmp eq i64 %x, 0
+  %r = zext i1 %t to i64
+  ret i64 %r
+}