From 7a4d0b9a1047b859d6af346e473437576d2790ba Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Sat, 15 Dec 2018 01:07:16 +0000
Subject: [PATCH] [X86] Make hasNoCarryFlagUses/hasNoSignedComparisonUses take
 an SDValue that indicates which result is the flag result. NFCI

hasNoCarryFlagUses hardcoded that the flag result is 1 and used that to filter which uses were of interest. hasNoSignedComparisonUses just assumes the only result is flags and checks whether any user of the node is a CopyToReg instruction.

After this patch we now do a result number check in both and rely on the caller to provide the result number.

This shouldn't change behavior it was just an odd difference between the two functions that I noticed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349222 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86ISelDAGToDAG.cpp | 39 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index ba8a8a8035e..67de43ec492 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -2193,16 +2193,16 @@ bool X86DAGToDAGISel::isSExtAbsoluteSymbolRef(unsigned Width, SDNode *N) const {
 
 /// Test whether the given X86ISD::CMP node has any uses which require the SF
 /// or OF bits to be accurate.
-static bool hasNoSignedComparisonUses(SDNode *N) {
+static bool hasNoSignedComparisonUses(SDValue Flags) {
   // Examine each user of the node.
-  for (SDNode::use_iterator UI = N->use_begin(),
-         UE = N->use_end(); UI != UE; ++UI) {
-    // Only examine CopyToReg uses.
-    if (UI->getOpcode() != ISD::CopyToReg)
-      return false;
+  for (SDNode::use_iterator UI = Flags->use_begin(), UE = Flags->use_end();
+         UI != UE; ++UI) {
+    // Only check things that use the flags.
+    if (UI.getUse().getResNo() != Flags.getResNo())
+      continue;
     // Only examine CopyToReg uses that copy to EFLAGS.
-    if (cast<RegisterSDNode>(UI->getOperand(1))->getReg() !=
-          X86::EFLAGS)
+    if (UI->getOpcode() != ISD::CopyToReg ||
+        cast<RegisterSDNode>(UI->getOperand(1))->getReg() != X86::EFLAGS)
       return false;
     // Examine each user of the CopyToReg use.
     for (SDNode::use_iterator FlagUI = UI->use_begin(),
@@ -2255,18 +2255,16 @@ static bool hasNoSignedComparisonUses(SDNode *N) {
 
 /// Test whether the given node which sets flags has any uses which require the
 /// CF flag to be accurate.
-static bool hasNoCarryFlagUses(SDNode *N) {
+static bool hasNoCarryFlagUses(SDValue Flags) {
   // Examine each user of the node.
-  for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end(); UI != UE;
-       ++UI) {
+  for (SDNode::use_iterator UI = Flags->use_begin(), UE = Flags->use_end();
+         UI != UE; ++UI) {
     // Only check things that use the flags.
-    if (UI.getUse().getResNo() != 1)
+    if (UI.getUse().getResNo() != Flags.getResNo())
       continue;
-    // Only examine CopyToReg uses.
-    if (UI->getOpcode() != ISD::CopyToReg)
-      return false;
     // Only examine CopyToReg uses that copy to EFLAGS.
-    if (cast<RegisterSDNode>(UI->getOperand(1))->getReg() != X86::EFLAGS)
+    if (UI->getOpcode() != ISD::CopyToReg ||
+        cast<RegisterSDNode>(UI->getOperand(1))->getReg() != X86::EFLAGS)
       return false;
     // Examine each user of the CopyToReg use.
     for (SDNode::use_iterator FlagUI = UI->use_begin(), FlagUE = UI->use_end();
@@ -2631,7 +2629,7 @@ bool X86DAGToDAGISel::foldLoadStoreIntoMemOperand(SDNode *Node) {
             (-OperandV).getMinSignedBits() <= 8) ||
            (MemVT == MVT::i64 && OperandV.getMinSignedBits() > 32 &&
             (-OperandV).getMinSignedBits() <= 32)) &&
-          hasNoCarryFlagUses(StoredVal.getNode())) {
+          hasNoCarryFlagUses(StoredVal.getValue(1))) {
         OperandV = -OperandV;
         Opc = Opc == X86ISD::ADD ? X86ISD::SUB : X86ISD::ADD;
       }
@@ -3717,7 +3715,7 @@ void X86DAGToDAGISel::Select(SDNode *Node) {
 
       if (isUInt<8>(Mask) &&
           (!(Mask & 0x80) || CmpVT == MVT::i8 ||
-           hasNoSignedComparisonUses(Node))) {
+           hasNoSignedComparisonUses(SDValue(Node, 0)))) {
         // For example, convert "testl %eax, $8" to "testb %al, $8"
         VT = MVT::i8;
         SubRegOp = X86::sub_8bit;
@@ -3725,7 +3723,7 @@ void X86DAGToDAGISel::Select(SDNode *Node) {
         MOpc = X86::TEST8mi;
       } else if (OptForMinSize && isUInt<16>(Mask) &&
                  (!(Mask & 0x8000) || CmpVT == MVT::i16 ||
-                  hasNoSignedComparisonUses(Node))) {
+                  hasNoSignedComparisonUses(SDValue(Node, 0)))) {
         // For example, "testl %eax, $32776" to "testw %ax, $32776".
         // NOTE: We only want to form TESTW instructions if optimizing for
         // min size. Otherwise we only save one byte and possibly get a length
@@ -3739,7 +3737,8 @@ void X86DAGToDAGISel::Select(SDNode *Node) {
                    // Without minsize 16-bit Cmps can get here so we need to
                    // be sure we calculate the correct sign flag if needed.
                    (CmpVT != MVT::i16 || !(Mask & 0x8000))) ||
-                  CmpVT == MVT::i32 || hasNoSignedComparisonUses(Node))) {
+                  CmpVT == MVT::i32 ||
+                  hasNoSignedComparisonUses(SDValue(Node, 0)))) {
         // For example, "testq %rax, $268468232" to "testl %eax, $268468232".
         // NOTE: We only want to run that transform if N0 is 32 or 64 bits.
         // Otherwize, we find ourselves in a position where we have to do
-- 
2.11.0