[PATCH] D34862: [CGP] Relax a bit restriction for optimizeMemoryInst to extend scope

[Serguei Katkov via Phabricator via llvm-commits]

skatkov updated this revision to Diff 105261.
skatkov added a comment.

This should be better, please take a look.


https://reviews.llvm.org/D34862

Files:
  lib/CodeGen/CodeGenPrepare.cpp
  test/CodeGen/X86/sink-gep-before-mem-inst.ll


Index: test/CodeGen/X86/sink-gep-before-mem-inst.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/sink-gep-before-mem-inst.ll
@@ -0,0 +1,25 @@
+; RUN: opt < %s -S -codegenprepare -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+define i64 @test.after(i8 addrspace(1)* readonly align 8) {
+; CHECK-LABEL: test.after
+; CHECK: sunkaddr
+entry:
+  %.0 = getelementptr inbounds i8, i8 addrspace(1)* %0, i64 8
+  %addr = bitcast i8 addrspace(1)* %.0 to i32 addrspace(1)*
+  br label %header
+
+header:
+  %addr.in.loop = phi i32 addrspace(1)* [ %addr, %entry ], [ %addr.after, %header ]
+  %local_2_ = phi i64 [ 0, %entry ], [ %.9, %header ]
+  %.7 = load i32, i32 addrspace(1)* %addr.in.loop, align 8
+  fence acquire
+  %.1 = getelementptr inbounds i8, i8 addrspace(1)* %0, i64 8
+  %addr.after = bitcast i8 addrspace(1)* %.1 to i32 addrspace(1)*
+  %.8 = sext i32 %.7 to i64
+  %.9 = add i64 %local_2_, %.8
+  %not. = icmp sgt i64 %.9, 999
+  br i1 %not., label %exit, label %header
+
+exit:
+  ret i64 %.9
+}
Index: lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- lib/CodeGen/CodeGenPrepare.cpp
+++ lib/CodeGen/CodeGenPrepare.cpp
@@ -4345,8 +4345,23 @@
   if (none_of(AddrModeInsts, [&](Value *V) {
         return IsNonLocalValue(V, MemoryInst->getParent());
       })) {
-    DEBUG(dbgs() << "CGP: Found      local addrmode: " << AddrMode << "\n");
-    return false;
+    // All instructions are in the same basic block.
+    // Let's ensure that all of them earlier in basic block than memory
+    // instruction.
+    SmallPtrSet<Instruction *, 16> AddrModeInstsSet(AddrModeInsts.begin(),
+                                                    AddrModeInsts.end());
+    unsigned Count = AddrModeInstsSet.size();
+    for (Instruction &I : *(MemoryInst->getParent())) {
+      if (&I == MemoryInst)
+        break;
+      Count -= AddrModeInstsSet.count(&I);
+      if (!Count)
+        break;
+    }
+    if (!Count) {
+      DEBUG(dbgs() << "CGP: Found      local addrmode: " << AddrMode << "\n");
+      return false;
+    }
   }
 
   // Insert this computation right after this user.  Since our caller is


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