Enhance boolean simplification to handle 16-/64-bit RDRAND

- RDRAND always clears the destination value when a random value is not
  available (i.e. CF == 0). This value is truncated or zero-extended as
  the false boolean value to be returned. Boolean simplification needs
  to skip this 'zext' or 'trunc' node.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178312 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 43 insertions, 6 deletions

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 709e9e8aae..e0f87c03b7 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -15821,8 +15821,9 @@ static SDValue checkBoolTestSetCCCombine(SDValue Cmp, X86::CondCode &CC) {
     // Quit if the constant is neither 0 or 1.
     return SDValue();
 
-  // Skip 'zext' node.
-  if (SetCC.getOpcode() == ISD::ZERO_EXTEND)
+  // Skip 'zext' or 'trunc' node.
+  if (SetCC.getOpcode() == ISD::ZERO_EXTEND ||
+      SetCC.getOpcode() == ISD::TRUNCATE)
     SetCC = SetCC.getOperand(0);
 
   switch (SetCC.getOpcode()) {
@@ -15841,9 +15842,13 @@ static SDValue checkBoolTestSetCCCombine(SDValue Cmp, X86::CondCode &CC) {
       return SDValue();
     // Quit if false value is not a constant.
     if (!FVal) {
-      // A special case for rdrand, where 0 is set if false cond is found.
       SDValue Op = SetCC.getOperand(0);
-      if (Op.getOpcode() != X86ISD::RDRAND)
+      // Skip 'zext' or 'trunc' node.
+      if (Op.getOpcode() == ISD::ZERO_EXTEND ||
+          Op.getOpcode() == ISD::TRUNCATE)
+        Op = Op.getOperand(0);
+      // A special case for rdrand, where 0 is set if false cond is found.
+      if (Op.getOpcode() != X86ISD::RDRAND || Op.getResNo() != 0)
         return SDValue();
     }
     // Quit if false value is not the constant 0 or 1.
diff --git a/test/CodeGen/X86/bool-simplify.ll b/test/CodeGen/X86/bool-simplify.ll
index 09eb5d1038..6d8e7fbe45 100644
--- a/test/CodeGen/X86/bool-simplify.ll
+++ b/test/CodeGen/X86/bool-simplify.ll
@@ -39,7 +39,22 @@ define i32 @bax(<2 x i64> %c) {
 ; CHECK: ret
 }
 
-define i32 @rnd(i32 %arg) nounwind uwtable {
+define i16 @rnd16(i16 %arg) nounwind uwtable {
+  %1 = tail call { i16, i32 } @llvm.x86.rdrand.16() nounwind
+  %2 = extractvalue { i16, i32 } %1, 0
+  %3 = extractvalue { i16, i32 } %1, 1
+  %4 = icmp eq i32 %3, 0
+  %5 = select i1 %4, i16 0, i16 %arg
+  %6 = add i16 %5, %2
+  ret i16 %6
+; CHECK: rnd16
+; CHECK: rdrand
+; CHECK: cmov
+; CHECK-NOT: cmov
+; CHECK: ret
+}
+
+define i32 @rnd32(i32 %arg) nounwind uwtable {
   %1 = tail call { i32, i32 } @llvm.x86.rdrand.32() nounwind
   %2 = extractvalue { i32, i32 } %1, 0
   %3 = extractvalue { i32, i32 } %1, 1
@@ -47,7 +62,22 @@ define i32 @rnd(i32 %arg) nounwind uwtable {
   %5 = select i1 %4, i32 0, i32 %arg
   %6 = add i32 %5, %2
   ret i32 %6
-; CHECK: rnd
+; CHECK: rnd32
+; CHECK: rdrand
+; CHECK: cmov
+; CHECK-NOT: cmov
+; CHECK: ret
+}
+
+define i64 @rnd64(i64 %arg) nounwind uwtable {
+  %1 = tail call { i64, i32 } @llvm.x86.rdrand.64() nounwind
+  %2 = extractvalue { i64, i32 } %1, 0
+  %3 = extractvalue { i64, i32 } %1, 1
+  %4 = icmp eq i32 %3, 0
+  %5 = select i1 %4, i64 0, i64 %arg
+  %6 = add i64 %5, %2
+  ret i64 %6
+; CHECK: rnd64
 ; CHECK: rdrand
 ; CHECK: cmov
 ; CHECK-NOT: cmov
@@ -55,4 +85,6 @@ define i32 @rnd(i32 %arg) nounwind uwtable {
 }
 
 declare i32 @llvm.x86.sse41.ptestz(<2 x i64>, <2 x i64>) nounwind readnone
+declare { i16, i32 } @llvm.x86.rdrand.16() nounwind
 declare { i32, i32 } @llvm.x86.rdrand.32() nounwind
+declare { i64, i32 } @llvm.x86.rdrand.64() nounwind