From: Michael Liao <michael.liao@intel.com>
Date: Fri, 13 Feb 2015 04:51:26 +0000 (+0000)
Subject: [InstCombine] Fix a bug when combining `icmp` from `ptrtoint`
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4235574ce3c02c2c8ba8885a61a4f056cf30f4c4;p=oota-llvm.git

[InstCombine] Fix a bug when combining `icmp` from `ptrtoint`

- First, there's a crash when we try to combine that pointers into `icmp`
  directly by creating a `bitcast`, which is invalid if that two pointers are
  from different address spaces.

- It's not always appropriate to cast one pointer to another if they are from
  different address spaces as that is not no-op cast. Instead, we only combine
  `icmp` from `ptrtoint` if that two pointers are of the same address space.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229063 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 27b6ed9d064..f48d89b426b 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1931,14 +1931,17 @@ Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
   if (DL && LHSCI->getOpcode() == Instruction::PtrToInt &&
       DL->getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) {
     Value *RHSOp = nullptr;
-    if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
+    if (PtrToIntOperator *RHSC = dyn_cast<PtrToIntOperator>(ICI.getOperand(1))) {
+      Value *RHSCIOp = RHSC->getOperand(0);
+      if (RHSCIOp->getType()->getPointerAddressSpace() ==
+          LHSCIOp->getType()->getPointerAddressSpace()) {
+        RHSOp = RHSC->getOperand(0);
+        // If the pointer types don't match, insert a bitcast.
+        if (LHSCIOp->getType() != RHSOp->getType())
+          RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
+      }
+    } else if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1)))
       RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
-    } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
-      RHSOp = RHSC->getOperand(0);
-      // If the pointer types don't match, insert a bitcast.
-      if (LHSCIOp->getType() != RHSOp->getType())
-        RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
-    }
 
     if (RHSOp)
       return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
diff --git a/test/Transforms/InstCombine/cast_ptr.ll b/test/Transforms/InstCombine/cast_ptr.ll
index 23006a84604..cc7a2bf1859 100644
--- a/test/Transforms/InstCombine/cast_ptr.ll
+++ b/test/Transforms/InstCombine/cast_ptr.ll
@@ -3,6 +3,8 @@
 
 target datalayout = "p:32:32-p1:32:32-p2:16:16"
 
+@global = global i8 0
+
 ; This shouldn't convert to getelementptr because the relationship
 ; between the arithmetic and the layout of allocated memory is
 ; entirely unknown.
@@ -47,10 +49,29 @@ define i1 @test2_as2_larger(i8 addrspace(2)* %a, i8 addrspace(2)* %b) {
   ret i1 %r
 }
 
+; These casts should not be folded away.
+; CHECK-LABEL: @test2_diff_as
+; CHECK: icmp sge i32 %i0, %i1
+define i1 @test2_diff_as(i8* %p, i8 addrspace(1)* %q) {
+  %i0 = ptrtoint i8* %p to i32
+  %i1 = ptrtoint i8 addrspace(1)* %q to i32
+  %r0 = icmp sge i32 %i0, %i1
+  ret i1 %r0
+}
+
+; These casts should not be folded away.
+; CHECK-LABEL: @test2_diff_as_global
+; CHECK: icmp sge i32 %i1
+define i1 @test2_diff_as_global(i8 addrspace(1)* %q) {
+  %i0 = ptrtoint i8* @global to i32
+  %i1 = ptrtoint i8 addrspace(1)* %q to i32
+  %r0 = icmp sge i32 %i1, %i0
+  ret i1 %r0
+}
+
 ; These casts should also be folded away.
 ; CHECK-LABEL: @test3(
 ; CHECK: icmp eq i8* %a, @global
-@global = global i8 0
 define i1 @test3(i8* %a) {
         %tmpa = ptrtoint i8* %a to i32
         %r = icmp eq i32 %tmpa, ptrtoint (i8* @global to i32)