From 2b6917b020207d2bca5c9917650244788d889a05 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Thu, 8 Jan 2015 00:51:32 +0000
Subject: [SelectionDAG] Allow targets to specify legality of extloads' result
 type (in addition to the memory type).

The *LoadExt* legalization handling used to only have one type, the
memory type.  This forced users to assume that as long as the extload
for the memory type was declared legal, and the result type was legal,
the whole extload was legal.

However, this isn't always the case.  For instance, on X86, with AVX,
this is legal:
    v4i32 load, zext from v4i8
but this isn't:
    v4i64 load, zext from v4i8
Whereas v4i64 is (arguably) legal, even without AVX2.

Note that the same thing was done a while ago for truncstores (r46140),
but I assume no one needed it yet for extloads, so here we go.

Calls to getLoadExtAction were changed to add the value type, found
manually in the surrounding code.

Calls to setLoadExtAction were mechanically changed, by wrapping the
call in a loop, to match previous behavior.  The loop iterates over
the MVT subrange corresponding to the memory type (FP vectors, etc...).
I also pulled neighboring setTruncStoreActions into some of the loops;
those shouldn't make a difference, as the additional types are illegal.
(e.g., i128->i1 truncstores on PPC.)

No functional change intended.

Differential Revision: http://reviews.llvm.org/D6532

llvm-svn: 225421
---
 llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

(limited to 'llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp')

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 1b3dc160a8e..ce8f96b7605 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -260,7 +260,7 @@ SelectionDAGLegalize::ExpandConstantFP(ConstantFPSDNode *CFP, bool UseCP) {
     if (ConstantFPSDNode::isValueValidForType(SVT, CFP->getValueAPF()) &&
         // Only do this if the target has a native EXTLOAD instruction from
         // smaller type.
-        TLI.isLoadExtLegal(ISD::EXTLOAD, SVT) &&
+        TLI.isLoadExtLegal(ISD::EXTLOAD, OrigVT, SVT) &&
         TLI.ShouldShrinkFPConstant(OrigVT)) {
       Type *SType = SVT.getTypeForEVT(*DAG.getContext());
       LLVMC = cast<ConstantFP>(ConstantExpr::getFPTrunc(LLVMC, SType));
@@ -944,7 +944,8 @@ void SelectionDAGLegalize::LegalizeLoadOps(SDNode *Node) {
       // nice to have an effective generic way of getting these benefits...
       // Until such a way is found, don't insist on promoting i1 here.
       (SrcVT != MVT::i1 ||
-       TLI.getLoadExtAction(ExtType, MVT::i1) == TargetLowering::Promote)) {
+       TLI.getLoadExtAction(ExtType, Node->getValueType(0), MVT::i1) ==
+         TargetLowering::Promote)) {
     // Promote to a byte-sized load if not loading an integral number of
     // bytes.  For example, promote EXTLOAD:i20 -> EXTLOAD:i24.
     unsigned NewWidth = SrcVT.getStoreSizeInBits();
@@ -1056,7 +1057,8 @@ void SelectionDAGLegalize::LegalizeLoadOps(SDNode *Node) {
     Chain = Ch;
   } else {
     bool isCustom = false;
-    switch (TLI.getLoadExtAction(ExtType, SrcVT.getSimpleVT())) {
+    switch (TLI.getLoadExtAction(ExtType, Node->getValueType(0),
+                                 SrcVT.getSimpleVT())) {
     default: llvm_unreachable("This action is not supported yet!");
     case TargetLowering::Custom:
       isCustom = true;
@@ -1088,7 +1090,8 @@ void SelectionDAGLegalize::LegalizeLoadOps(SDNode *Node) {
       break;
     }
     case TargetLowering::Expand:
-      if (!TLI.isLoadExtLegal(ISD::EXTLOAD, SrcVT) && TLI.isTypeLegal(SrcVT)) {
+      if (!TLI.isLoadExtLegal(ISD::EXTLOAD, Node->getValueType(0),
+                              SrcVT) && TLI.isTypeLegal(SrcVT)) {
         SDValue Load = DAG.getLoad(SrcVT, dl, Chain, Ptr, LD->getMemOperand());
         unsigned ExtendOp;
         switch (ExtType) {
-- 
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