[llvm] r222123 - Fix optimisations of SELECT_CC which assumed result is boolean

[Oliver Stannard]

Author: olista01
Date: Mon Nov 17 04:49:31 2014
New Revision: 222123

URL: http://llvm.org/viewvc/llvm-project?rev=222123&view=rev
Log:
Fix optimisations of SELECT_CC which assumed result is boolean

Some optimisations in DAGCombiner cause miscompilations for targets that use
TargetLowering::UndefinedBooleanContent, because they assume that the results
of a SELECT_CC node are boolean values, and can be safely ANDed, ORed and
XORed. These optimisations are only valid for targets that use
ZeroOrOneBooleanContent or ZeroOrNegativeOneBooleanContent.

This is a follow-up to D6210/r221693.


Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/ARM/select_xform.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=222123&r1=222122&r2=222123&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Nov 17 04:49:31 2014
@@ -645,6 +645,10 @@ bool DAGCombiner::isSetCCEquivalent(SDVa
       !TLI.isConstFalseVal(N.getOperand(3).getNode()))
     return false;
 
+  if (TLI.getBooleanContents(N.getValueType()) ==
+      TargetLowering::UndefinedBooleanContent)
+    return false;
+
   LHS = N.getOperand(0);
   RHS = N.getOperand(1);
   CC  = N.getOperand(4);
@@ -3826,8 +3830,7 @@ SDValue DAGCombiner::visitXOR(SDNode *N)
     return RXOR;
 
   // fold !(x cc y) -> (x !cc y)
-  if (N1C && N1C->getAPIntValue().isAllOnesValue() &&
-      isSetCCEquivalent(N0, LHS, RHS, CC)) {
+  if (TLI.isConstTrueVal(N1.getNode()) && isSetCCEquivalent(N0, LHS, RHS, CC)) {
     bool isInt = LHS.getValueType().isInteger();
     ISD::CondCode NotCC = ISD::getSetCCInverse(cast<CondCodeSDNode>(CC)->get(),
                                                isInt);

Modified: llvm/trunk/test/CodeGen/ARM/select_xform.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/select_xform.ll?rev=222123&r1=222122&r2=222123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/select_xform.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/select_xform.ll Mon Nov 17 04:49:31 2014
@@ -224,18 +224,108 @@ entry:
 }
 
 ; Do not fold the xor into the select
-define i32 @t15(i32 %p1, i32 %p2, i32 %p3) {
+define i32 @t15(i32 %p) {
 entry:
-; ARM: cmp            r0, #8
-; ARM: mov{{(le|gt)}} [[REG:r[0-9]+]], {{r[0-9]+}}
-; ARM: eor            r0, [[REG]], #1
-
-; T2: cmp       r0, #8
-; T2: it        [[CC:(le|gt)]]
-; T2: mov[[CC]] [[REG:r[0-9]+]], {{r[0-9]+}}
-; T2: eor       r0, [[REG:r[0-9]+]], #1
-  %cmp = icmp sgt i32 %p1, 8
-  %a = select i1 %cmp, i32 %p2, i32 %p3
+; ARM-LABEL: t15:
+; ARM: mov     [[REG:r[0-9]+]], #2
+; ARM: cmp     r0, #8
+; ARM: movwgt  [[REG:r[0-9]+]], #1
+; ARM: eor     r0, [[REG:r[0-9]+]], #1
+
+; T2-LABEL: t15:
+; T2: movs    [[REG:r[0-9]+]], #2
+; T2: cmp     [[REG:r[0-9]+]], #8
+; T2: it      gt
+; T2: movgt   [[REG:r[0-9]+]], #1
+; T2: eor     r0, [[REG:r[0-9]+]], #1
+  %cmp = icmp sgt i32 %p, 8
+  %a = select i1 %cmp, i32 1, i32 2
   %xor = xor i32 %a, 1
   ret i32 %xor
 }
+
+define i32 @t16(i32 %x, i32 %y) {
+entry:
+; ARM-LABEL: t16:
+; ARM: and r0, {{r[0-9]+}}, {{r[0-9]+}}
+
+; T2-LABEL: t16:
+; T2: ands r0, {{r[0-9]+}}
+  %cmp = icmp eq i32 %x, 0
+  %cond = select i1 %cmp, i32 5, i32 2
+  %cmp1 = icmp eq i32 %y, 0
+  %cond2 = select i1 %cmp1, i32 3, i32 4
+  %and = and i32 %cond2, %cond
+  ret i32 %and
+}
+
+define i32 @t17(i32 %x, i32 %y) #0 {
+entry:
+; ARM-LABEL: t17:
+; ARM: and r0, {{r[0-9]+}}, {{r[0-9]+}}
+
+; T2-LABEL: t17:
+; T2: ands r0, {{r[0-9]+}}
+  %cmp = icmp eq i32 %x, -1
+  %cond = select i1 %cmp, i32 5, i32 2
+  %cmp1 = icmp eq i32 %y, -1
+  %cond2 = select i1 %cmp1, i32 3, i32 4
+  %and = and i32 %cond2, %cond
+  ret i32 %and
+}
+
+define i32 @t18(i32 %x, i32 %y) #0 {
+entry:
+; ARM-LABEL: t18:
+; ARM: and r0, {{r[0-9]+}}, {{r[0-9]+}}
+
+; T2-LABEL: t18:
+; T2: and.w r0, {{r[0-9]+}}
+  %cmp = icmp ne i32 %x, 0
+  %cond = select i1 %cmp, i32 5, i32 2
+  %cmp1 = icmp ne i32 %x, -1
+  %cond2 = select i1 %cmp1, i32 3, i32 4
+  %and = and i32 %cond2, %cond
+  ret i32 %and
+}
+
+define i32 @t19(i32 %x, i32 %y) #0 {
+entry:
+; ARM-LABEL: t19:
+; ARM: orr r0, {{r[0-9]+}}, {{r[0-9]+}}
+
+; T2-LABEL: t19:
+; T2: orrs r0, {{r[0-9]+}}
+  %cmp = icmp ne i32 %x, 0
+  %cond = select i1 %cmp, i32 5, i32 2
+  %cmp1 = icmp ne i32 %y, 0
+  %cond2 = select i1 %cmp1, i32 3, i32 4
+  %or = or i32 %cond2, %cond
+  ret i32 %or
+}
+
+define i32 @t20(i32 %x, i32 %y) #0 {
+entry:
+; ARM-LABEL: t20:
+; ARM: orr r0, {{r[0-9]+}}, {{r[0-9]+}}
+
+; T2-LABEL: t20:
+; T2: orrs r0, {{r[0-9]+}}
+  %cmp = icmp ne i32 %x, -1
+  %cond = select i1 %cmp, i32 5, i32 2
+  %cmp1 = icmp ne i32 %y, -1
+  %cond2 = select i1 %cmp1, i32 3, i32 4
+  %or = or i32 %cond2, %cond
+  ret i32 %or
+}
+
+define  <2 x i32> @t21(<2 x i32> %lhs, <2 x i32> %rhs) {
+; CHECK-LABEL: t21:
+; CHECK-NOT: eor
+; CHECK: mvn
+; CHECK-NOT: eor
+  %tst = icmp eq <2 x i32> %lhs, %rhs
+  %ntst = xor <2 x i1> %tst, <i1 1 , i1 undef>
+  %btst = sext <2 x i1> %ntst to <2 x i32>
+  ret <2 x i32> %btst
+}