[PATCH] DAGCombiner: Respect the result of TLI.getBooleanContents() when expanding SETCC

[Tom Stellard]

On Thu, Feb 28, 2013 at 05:29:10PM +0100, Duncan Sands wrote:
> Hi Tom, this is OK with a testcase.
> 

Hi Duncan,

Here is an updated patch with a test case for R600.

-Tom

> Ciao, Duncan.
> 
> On 28/02/13 00:16, Tom Stellard wrote:
> > From: Tom Stellard <thomas.stellard at amd.com>
> >
> > ---
> >   lib/CodeGen/SelectionDAG/LegalizeDAG.cpp |   14 +++++++++++++-
> >   1 files changed, 13 insertions(+), 1 deletions(-)
> >
> > diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
> > index f085e44..743a9da 100644
> > --- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
> > +++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
> > @@ -3632,8 +3632,20 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
> >       // Otherwise, SETCC for the given comparison type must be completely
> >       // illegal; expand it into a SELECT_CC.
> >       EVT VT = Node->getValueType(0);
> > +    int TrueValue;
> > +    switch(TLI.getBooleanContents(VT.isVector())) {
> > +    default: assert(!"Unhandled BooleanContent value");
> > +    case TargetLowering::ZeroOrOneBooleanContent:
> > +    case TargetLowering::UndefinedBooleanContent:
> > +      TrueValue = 1;
> > +      break;
> > +    case TargetLowering::ZeroOrNegativeOneBooleanContent:
> > +      TrueValue = -1;
> > +      break;
> > +    }
> >       Tmp1 = DAG.getNode(ISD::SELECT_CC, dl, VT, Tmp1, Tmp2,
> > -                       DAG.getConstant(1, VT), DAG.getConstant(0, VT), Tmp3);
> > +                       DAG.getConstant(TrueValue, VT), DAG.getConstant(0, VT),
> > +                       Tmp3);
> >       Results.push_back(Tmp1);
> >       break;
> >     }
> >
> 
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-------------- next part --------------
>From 433570da10c7aca49f44680bf348e3aa13029d86 Mon Sep 17 00:00:00 2001
From: Tom Stellard <thomas.stellard at amd.com>
Date: Wed, 27 Feb 2013 18:08:46 -0500
Subject: [PATCH 2/7] LegalizeDAG: Respect the result of
 TLI.getBooleanContents() when expanding SETCC

---
 lib/CodeGen/SelectionDAG/LegalizeDAG.cpp          |   14 ++++++++++-
 test/CodeGen/R600/legalizedag-bug-expand-setcc.ll |   26 +++++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletions(-)
 create mode 100644 test/CodeGen/R600/legalizedag-bug-expand-setcc.ll

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index f085e44..743a9da 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3632,8 +3632,20 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     // Otherwise, SETCC for the given comparison type must be completely
     // illegal; expand it into a SELECT_CC.
     EVT VT = Node->getValueType(0);
+    int TrueValue;
+    switch(TLI.getBooleanContents(VT.isVector())) {
+    default: assert(!"Unhandled BooleanContent value");
+    case TargetLowering::ZeroOrOneBooleanContent:
+    case TargetLowering::UndefinedBooleanContent:
+      TrueValue = 1;
+      break;
+    case TargetLowering::ZeroOrNegativeOneBooleanContent:
+      TrueValue = -1;
+      break;
+    }
     Tmp1 = DAG.getNode(ISD::SELECT_CC, dl, VT, Tmp1, Tmp2,
-                       DAG.getConstant(1, VT), DAG.getConstant(0, VT), Tmp3);
+                       DAG.getConstant(TrueValue, VT), DAG.getConstant(0, VT),
+                       Tmp3);
     Results.push_back(Tmp1);
     break;
   }
diff --git a/test/CodeGen/R600/legalizedag-bug-expand-setcc.ll b/test/CodeGen/R600/legalizedag-bug-expand-setcc.ll
new file mode 100644
index 0000000..1aae7f9
--- /dev/null
+++ b/test/CodeGen/R600/legalizedag-bug-expand-setcc.ll
@@ -0,0 +1,26 @@
+; RUN: llc < %s -march=r600 -mcpu=redwood | FileCheck %s
+
+; This tests a bug where LegalizeDAG was not checking the target's
+; BooleanContents value and always using one for true, when expanding
+; setcc to select_cc.
+;
+; This bug caused the icmp IR instruction to be expanded to two machine
+; instructions, when only one is needed.
+;
+
+; CHECK: @setcc_expand
+; CHECK: SET
+; CHECK-NOT: CND
+define void @setcc_expand(i32 addrspace(1)* %out, i32 %in) {
+entry:
+  %0 = icmp eq i32 %in, 5
+  br i1 %0, label %IF, label %ENDIF
+IF:
+  %1 = getelementptr i32 addrspace(1)* %out, i32 1
+  store i32 0, i32 addrspace(1)* %1
+  br label %ENDIF
+
+ENDIF:
+  store i32 0, i32 addrspace(1)* %out
+  ret void
+}
-- 
1.7.8.6