[PATCH] D24729: Don't look through addrspacecast in GetPointerBaseWithConstantOffset

[Artur Pilipenko via llvm-commits]

apilipenko updated this revision to Diff 72166.
apilipenko added a comment.

Let GetPointerBaseWithConstantOffset look through addrspace casts which doesn't change pointer size


https://reviews.llvm.org/D24729

Files:
  lib/Analysis/ValueTracking.cpp
  test/Transforms/GVN/PRE/rle-addrspace-cast.ll
  test/Transforms/GVN/PRE/rle.ll
  test/Transforms/GVN/addrspace-cast.ll

Index: test/Transforms/GVN/addrspace-cast.ll
===================================================================
--- /dev/null
+++ test/Transforms/GVN/addrspace-cast.ll
@@ -0,0 +1,21 @@
+; RUN: opt < %s -gvn -S | FileCheck %s
+target datalayout = "e-m:e-p:16:16-p1:32:16-i32:16-i64:16-n8:16"
+
+; In cases where two address spaces do not have the same size pointer, the
+; input for the addrspacecast should not be used as a substitute for itself
+; when manipulating the pointer.
+
+; Check that we don't hit the assert in this scenario
+define i8 @test(i32 %V, i32* %P) {
+; CHECK-LABEL: @test(
+; CHECK: load
+  %P1 = getelementptr inbounds i32, i32* %P, i16 16
+
+  store i32 %V, i32* %P1
+
+  %P2 = addrspacecast i32* %P1 to i8 addrspace(1)*
+  %P3 = getelementptr i8, i8 addrspace(1)* %P2, i32 2
+
+  %A = load i8, i8 addrspace(1)* %P3
+  ret i8 %A
+}
Index: test/Transforms/GVN/PRE/rle.ll
===================================================================
--- test/Transforms/GVN/PRE/rle.ll
+++ test/Transforms/GVN/PRE/rle.ll
@@ -318,19 +318,6 @@
 ; CHECK: ret i8
 }
 
-define i8 @coerce_offset0_addrspacecast(i32 %V, i32* %P) {
-  store i32 %V, i32* %P
-
-  %P2 = addrspacecast i32* %P to i8 addrspace(1)*
-  %P3 = getelementptr i8, i8 addrspace(1)* %P2, i32 2
-
-  %A = load i8, i8 addrspace(1)* %P3
-  ret i8 %A
-; CHECK-LABEL: @coerce_offset0_addrspacecast(
-; CHECK-NOT: load
-; CHECK: ret i8
-}
-
 ;; non-local i32/float -> i8 load forwarding.
 define i8 @coerce_offset_nonlocal0(i32* %P, i1 %cond) {
   %P2 = bitcast i32* %P to float*
Index: test/Transforms/GVN/PRE/rle-addrspace-cast.ll
===================================================================
--- /dev/null
+++ test/Transforms/GVN/PRE/rle-addrspace-cast.ll
@@ -0,0 +1,14 @@
+; RUN: opt < %s -basicaa -gvn -S -die | FileCheck %s
+
+define i8 @coerce_offset0_addrspacecast(i32 %V, i32* %P) {
+  store i32 %V, i32* %P
+
+  %P2 = addrspacecast i32* %P to i8 addrspace(1)*
+  %P3 = getelementptr i8, i8 addrspace(1)* %P2, i32 2
+
+  %A = load i8, i8 addrspace(1)* %P3
+  ret i8 %A
+; CHECK-LABEL: @coerce_offset0_addrspacecast(
+; CHECK-NOT: load
+; CHECK: ret i8
+}
Index: lib/Analysis/ValueTracking.cpp
===================================================================
--- lib/Analysis/ValueTracking.cpp
+++ lib/Analysis/ValueTracking.cpp
@@ -2840,9 +2840,14 @@
       ByteOffset += GEPOffset;
 
       Ptr = GEP->getPointerOperand();
-    } else if (Operator::getOpcode(Ptr) == Instruction::BitCast ||
-               Operator::getOpcode(Ptr) == Instruction::AddrSpaceCast) {
+    } else if (Operator::getOpcode(Ptr) == Instruction::BitCast) {
       Ptr = cast<Operator>(Ptr)->getOperand(0);
+    } else if (AddrSpaceCastInst *ASCI = dyn_cast<AddrSpaceCastInst>(Ptr)) {
+      Value *SourcePtr = ASCI->getPointerOperand();
+      // Don't look through addrspace cast which changes pointer size
+      if (BitWidth != DL.getPointerTypeSizeInBits(SourcePtr->getType()))
+        break;
+      Ptr = SourcePtr;
     } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(Ptr)) {
       if (GA->isInterposable())
         break;


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