add X86-specific DAG optimization to simplify boolean test

- if a boolean test (X86ISD::CMP or X86ISD:SUB) checks a boolean value
  generated from X86ISD::SETCC, try to simplify the boolean value
  generation and checking by reusing the original EFLAGS with proper
  condition code
- add hooks to X86 specific SETCC/BRCOND/CMOV, the major 3 places
  consuming EFLAGS

part of patches fixing PR12312

llvm-svn: 161687

1 files changed, 42 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/bool-simplify.ll b/llvm/test/CodeGen/X86/bool-simplify.ll
new file mode 100644
index 00000000000..0cb9fd9bc53
--- /dev/null
+++ b/llvm/test/CodeGen/X86/bool-simplify.ll
@@ -0,0 +1,42 @@
+; RUN: llc < %s -march=x86-64 -mattr=+sse41,-avx | FileCheck %s
+
+define i32 @foo(<2 x i64> %c, i32 %a, i32 %b) {
+  %t1 = call i32 @llvm.x86.sse41.ptestz(<2 x i64> %c, <2 x i64> %c)
+  %t2 = icmp ne i32 %t1, 0
+  %t3 = select i1 %t2, i32 %a, i32 %b
+  ret i32 %t3
+; CHECK: foo
+; CHECK: ptest
+; CHECK-NOT: testl
+; CHECK: cmov
+; CHECK: ret
+}
+
+define i32 @bar(<2 x i64> %c) {
+entry:
+  %0 = call i32 @llvm.x86.sse41.ptestz(<2 x i64> %c, <2 x i64> %c)
+  %1 = icmp ne i32 %0, 0
+  br i1 %1, label %if-true-block, label %endif-block
+if-true-block:                                    ; preds = %entry
+  ret i32 0
+endif-block:                                      ; preds = %entry,
+  ret i32 1
+; CHECK: bar
+; CHECK: ptest
+; CHECK-NOT: testl
+; CHECK: jne
+; CHECK: ret
+}
+
+define i32 @bax(<2 x i64> %c) {
+  %t1 = call i32 @llvm.x86.sse41.ptestz(<2 x i64> %c, <2 x i64> %c)
+  %t2 = icmp eq i32 %t1, 1
+  %t3 = zext i1 %t2 to i32
+  ret i32 %t3
+; CHECK: bax
+; CHECK: ptest
+; CHECK-NOT: cmpl
+; CHECK: ret
+}
+
+declare i32 @llvm.x86.sse41.ptestz(<2 x i64>, <2 x i64>) nounwind readnone