[PATCH] D39841: [CodeGenPrepare] Check that erased sunken address are not reused

[Simon Dardis via Phabricator via llvm-commits]

sdardis updated this revision to Diff 122430.
sdardis added a comment.

Address review comments.


https://reviews.llvm.org/D39841

Files:
  lib/CodeGen/CodeGenPrepare.cpp
  test/Transforms/CodeGenPrepare/Mips/lit.local.cfg
  test/Transforms/CodeGenPrepare/Mips/pr35209.ll


Index: test/Transforms/CodeGenPrepare/Mips/pr35209.ll
===================================================================
--- /dev/null
+++ test/Transforms/CodeGenPrepare/Mips/pr35209.ll
@@ -0,0 +1,64 @@
+; RUN: opt -S -mtriple=mips64-mti-linux-gnu -codegenprepare < %s | FileCheck %s
+
+; Test that if an address that was sunk from a dominating bb, used in a
+; select that is erased along with its' trivally dead operand, that the
+; sunken address is not reused if the same address computation occurs
+; after the select. Previously, this caused a ICE.
+
+%struct.az = type { i32, %struct.bt* }
+%struct.bt = type { i32 }
+%struct.f = type { %struct.ax, %union.anon }
+%struct.ax = type { %struct.az* }
+%union.anon = type { %struct.bd }
+%struct.bd = type { i64 }
+%struct.bg = type { i32, i32 }
+%struct.ap = type { i32, i32 }
+
+ at ch = common global %struct.f zeroinitializer, align 8
+ at j = common global %struct.az* null, align 8
+ at ck = common global i32 0, align 4
+ at h = common global i32 0, align 4
+ at .str = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
+
+define internal void @probestart() {
+entry:
+  %0 = load %struct.az*, %struct.az** @j, align 8
+  %bw = getelementptr inbounds %struct.az, %struct.az* %0, i64 0, i32 1
+  %1 = load i32, i32* @h, align 4
+  %cond = icmp eq i32 %1, 0
+  br i1 %cond, label %sw.bb, label %cl
+
+sw.bb:                                            ; preds = %entry
+  %call = tail call inreg { i64, i64 } @ba(i32* bitcast (%struct.f* @ch to i32*))
+  br label %cl
+
+cl:                                               ; preds = %sw.bb, %entry
+  %2 = load %struct.bt*, %struct.bt** %bw, align 8
+  %tobool = icmp eq %struct.bt* %2, null
+  %3 = load i32, i32* @ck, align 4
+  %.sink5 = select i1 %tobool, i32* getelementptr (%struct.bg, %struct.bg* bitcast (%union.anon* getelementptr inbounds (%struct.f, %struct.f* @ch, i64 0, i32 1) to %struct.bg*), i64 0, i32 1), i32* getelementptr (%struct.ap, %struct.ap* bitcast (%union.anon* getelementptr inbounds (%struct.f, %struct.f* @ch, i64 0, i32 1) to %struct.ap*), i64 0, i32 1)
+  store i32 %3, i32* %.sink5, align 4
+  store i32 1, i32* bitcast (i64* getelementptr inbounds (%struct.f, %struct.f* @ch, i64 0, i32 1, i32 0, i32 0) to i32*), align 8
+  %4 = load %struct.bt*, %struct.bt** %bw, align 8
+  tail call void (i8*, ...) @a(i8* getelementptr inbounds ([1 x i8], [1 x i8]* @.str, i64 0, i64 0), %struct.bt* %4)
+  ret void
+}
+
+; CHECK-LABEL: @probestart()
+; CHECK-LABEL: entry:
+; CHECK: %[[I0:[0-9]+]] = load %struct.az*, %struct.az** @j
+; CHECK-LABEL: cl:
+
+; CHECK-NOT: %{{[0-9]+}}  = load %struct.bt*, %struct.bt** %bw
+; CHECK-NOT: %{{[.a-z0-9]}} = select
+; CHECK-NOT: %{{[0-9]+}}  = load %struct.bt*, %struct.bt** %bw
+
+; CHECK: %[[I1:[0-9]+]] = bitcast %struct.az* %[[I0]] to i8*
+; CHECK-NEXT: %sunkaddr = getelementptr i8, i8* %[[I1]], i64 8
+; CHECK-NEXT: %[[I2:[0-9]+]] = bitcast i8* %sunkaddr to %struct.bt**
+; CHECK-NEXT: %{{[0-9]+}} = load %struct.bt*, %struct.bt** %[[I2]]
+; CHECK-NEXT: tail call void (i8*, ...) @a
+
+declare inreg { i64, i64 } @ba(i32*)
+
+declare void @a(i8*, ...)
Index: test/Transforms/CodeGenPrepare/Mips/lit.local.cfg
===================================================================
--- /dev/null
+++ test/Transforms/CodeGenPrepare/Mips/lit.local.cfg
@@ -0,0 +1,2 @@
+if not 'Mips' in config.root.targets:
+    config.unsupported = True
Index: lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- lib/CodeGen/CodeGenPrepare.cpp
+++ lib/CodeGen/CodeGenPrepare.cpp
@@ -4358,7 +4358,12 @@
   // Now that we determined the addressing expression we want to use and know
   // that we have to sink it into this block.  Check to see if we have already
   // done this for some other load/store instr in this block.  If so, reuse the
-  // computation.
+  // computation.  Before attempting reuse, check if the address is valid as it
+  // may have been erased.
+  auto I = SunkAddrs.find(Addr);
+  if (I != SunkAddrs.end() && I->second && I->second->user_empty())
+    SunkAddrs.erase(I);
+
   Value *&SunkAddr = SunkAddrs[Addr];
   if (SunkAddr) {
     DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "


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