[llvm-commits] [llvm] r169719 - in /llvm/trunk: lib/Transforms/Scalar/SROA.cpp test/Transforms/SROA/basictest.ll test/Transforms/SROA/big-endian.ll

[Chandler Carruth]

Author: chandlerc
Date: Sun Dec  9 18:54:45 2012
New Revision: 169719

URL: http://llvm.org/viewvc/llvm-project?rev=169719&view=rev
Log:
Fix PR14548: SROA was crashing on a mixture of i1 and i8 loads and stores.

When SROA was evaluating a mixture of i1 and i8 loads and stores, in
just a particular case, it would tickle a latent bug where we compared
bits to bytes rather than bits to bits. As a consequence of the latent
bug, we would allow integers through which were not byte-size multiples,
a situation the later rewriting code was never intended to handle.

In release builds this could trigger all manner of oddities, but the
reported issue in PR14548 was forming invalid bitcast instructions.

The only downside of this fix is that it makes it more clear that SROA
in its current form is not capable of handling mixed i1 and i8 loads and
stores. Sometimes with the previous code this would work by luck, but
usually it would crash, so I'm not terribly worried. I'll watch the LNT
numbers just to be sure.

Modified:
    llvm/trunk/lib/Transforms/Scalar/SROA.cpp
    llvm/trunk/test/Transforms/SROA/basictest.ll
    llvm/trunk/test/Transforms/SROA/big-endian.ll

Modified: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SROA.cpp?rev=169719&r1=169718&r2=169719&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SROA.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp Sun Dec  9 18:54:45 2012
@@ -2184,7 +2184,7 @@
       if (RelBegin == 0 && RelEnd == Size)
         WholeAllocaOp = true;
       if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) {
-        if (ITy->getBitWidth() < TD.getTypeStoreSize(ITy))
+        if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy))
           return false;
         continue;
       }
@@ -2200,7 +2200,7 @@
       if (RelBegin == 0 && RelEnd == Size)
         WholeAllocaOp = true;
       if (IntegerType *ITy = dyn_cast<IntegerType>(ValueTy)) {
-        if (ITy->getBitWidth() < TD.getTypeStoreSize(ITy))
+        if (ITy->getBitWidth() < TD.getTypeStoreSizeInBits(ITy))
           return false;
         continue;
       }

Modified: llvm/trunk/test/Transforms/SROA/basictest.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SROA/basictest.ll?rev=169719&r1=169718&r2=169719&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SROA/basictest.ll (original)
+++ llvm/trunk/test/Transforms/SROA/basictest.ll Sun Dec  9 18:54:45 2012
@@ -1147,3 +1147,32 @@
   ret void
 ; CHECK: ret
 }
+
+define void @PR14548(i1 %x) {
+; Handle a mixture of i1 and i8 loads and stores to allocas. This particular
+; pattern caused crashes and invalid output in the PR, and its nature will
+; trigger a mixture in several permutations as we resolve each alloca
+; iteratively.
+; Note that we don't do a particularly good *job* of handling these mixtures,
+; but the hope is that this is very rare.
+; CHECK: @PR14548
+
+entry:
+  %a = alloca <{ i1 }>, align 8
+  %b = alloca <{ i1 }>, align 8
+; Nothing of interest is simplified here.
+; CHECK: alloca
+; CHECK: alloca
+
+  %b.i1 = bitcast <{ i1 }>* %b to i1*
+  store i1 %x, i1* %b.i1, align 8
+  %b.i8 = bitcast <{ i1 }>* %b to i8*
+  %foo = load i8* %b.i8, align 1
+
+  %a.i8 = bitcast <{ i1 }>* %a to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a.i8, i8* %b.i8, i32 1, i32 1, i1 false) nounwind
+  %bar = load i8* %a.i8, align 1
+  %a.i1 = getelementptr inbounds <{ i1 }>* %a, i32 0, i32 0
+  %baz = load i1* %a.i1, align 1
+  ret void
+}

Modified: llvm/trunk/test/Transforms/SROA/big-endian.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SROA/big-endian.ll?rev=169719&r1=169718&r2=169719&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SROA/big-endian.ll (original)
+++ llvm/trunk/test/Transforms/SROA/big-endian.ll Sun Dec  9 18:54:45 2012
@@ -82,14 +82,9 @@
 
   %a0i16ptr = bitcast i8* %a0ptr to i16*
   store i16 1, i16* %a0i16ptr
-; CHECK:      %[[mask0:.*]] = and i16 1, -16
-
-  %a1i4ptr = bitcast i8* %a1ptr to i4*
-  store i4 1, i4* %a1i4ptr
-; CHECK-NEXT: %[[insert0:.*]] = or i16 %[[mask0]], 1
 
   store i8 1, i8* %a2ptr
-; CHECK-NEXT: %[[mask1:.*]] = and i40 undef, 4294967295
+; CHECK:      %[[mask1:.*]] = and i40 undef, 4294967295
 ; CHECK-NEXT: %[[insert1:.*]] = or i40 %[[mask1]], 4294967296
 
   %a3i24ptr = bitcast i8* %a3ptr to i24*
@@ -110,7 +105,7 @@
   %ai = load i56* %aiptr
   %ret = zext i56 %ai to i64
   ret i64 %ret
-; CHECK-NEXT: %[[ext4:.*]] = zext i16 %[[insert0]] to i56
+; CHECK-NEXT: %[[ext4:.*]] = zext i16 1 to i56
 ; CHECK-NEXT: %[[shift4:.*]] = shl i56 %[[ext4]], 40
 ; CHECK-NEXT: %[[mask4:.*]] = and i56 %[[insert3]], 1099511627775
 ; CHECK-NEXT: %[[insert4:.*]] = or i56 %[[mask4]], %[[shift4]]