[Beignet] [PATCH] GBE: fix regression caused by simple block optimization.

[Luo, Xionghu]

LGTM.
Add comments for why unaligned store instruction not excluded before push, please.
Thanks.

Luo Xionghu
Best Regards

-----Original Message-----
From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of Zhigang Gong
Sent: Thursday, October 23, 2014 2:26 PM
To: beignet at lists.freedesktop.org
Cc: Gong, Zhigang
Subject: [Beignet] [PATCH] GBE: fix regression caused by simple block optimization.

Almost all 64bit related instructions and unaligned load instruction should be complex instruction. We need to exclude them from simple block.

Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
---
 backend/src/backend/gen_insn_selection.cpp | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/backend/src/backend/gen_insn_selection.cpp b/backend/src/backend/gen_insn_selection.cpp
index 1a37ef1..605fdd5 100644
--- a/backend/src/backend/gen_insn_selection.cpp
+++ b/backend/src/backend/gen_insn_selection.cpp
@@ -407,6 +407,8 @@ namespace gbe
     void matchBasicBlock(const ir::BasicBlock &bb, uint32_t insnNum);
     /*! a simple block can use predication instead of if/endif*/
     bool isSimpleBlock(const ir::BasicBlock &bb, uint32_t insnNum);
+    /*! an instruction has a QWORD family src or dst operand. */
+    bool hasQWord(const ir::Instruction &insn);
     /*! A root instruction needs to be generated */
     bool isRoot(const ir::Instruction &insn) const;
 
@@ -1494,6 +1496,20 @@ namespace gbe
     return false;
   }
 
+  bool Selection::Opaque::hasQWord(const ir::Instruction &insn) {
+    for (uint32_t i = 0; i < insn.getSrcNum(); i++) {
+      const ir::Register reg = insn.getSrc(i);
+      if (getRegisterFamily(reg) == ir::FAMILY_QWORD)
+        return true;
+    }
+    for (uint32_t i = 0; i < insn.getDstNum(); i++) {
+      const ir::Register reg = insn.getDst(i);
+      if (getRegisterFamily(reg) == ir::FAMILY_QWORD)
+        return true;
+    }
+    return false;
+  }
+
   bool Selection::Opaque::isSimpleBlock(const ir::BasicBlock &bb, uint32_t insnNum) {
 
     // FIXME should include structured innermost if/else/endif @@ -1511,6 +1527,18 @@ namespace gbe
          insn.getOpcode() == ir::OP_SIMD_ALL ||
          insn.getOpcode() == ir::OP_ELSE)
         return false;
+
+      // Most of the QWord(long) related instruction introduce some CMP or
+      // more than 10 actual instructions at latter stage.
+      if (hasQWord(insn))
+        return false;
+
+      // Unaligned load may introduce CMP instruction.
+      if ( insn.isMemberOf<ir::LoadInstruction>()) {
+        const ir::LoadInstruction &ld = ir::cast<ir::LoadInstruction>(insn);
+        if (!ld.isAligned())
+          return false;
+      }
     }
 
     // there would generate a extra CMP instruction for predicated BRA with extern flag,
--
1.8.3.2

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