[llvm-branch-commits] [llvm-branch] r260640 - Merging r260587:

[Hans Wennborg via llvm-branch-commits]

Author: hans
Date: Thu Feb 11 19:42:38 2016
New Revision: 260640

URL: http://llvm.org/viewvc/llvm-project?rev=260640&view=rev
Log:
Merging r260587:
------------------------------------------------------------------------
r260587 | pete | 2016-02-11 13:10:40 -0800 (Thu, 11 Feb 2016) | 13 lines

Set load alignment on aggregate loads.

When optimizing a extractvalue(load), we generate a load from the
aggregate type.  This load didn't have alignment set and so would
get the alignment of the type.  This breaks when the type is packed
and so the alignment should be lower.

For example, loading { int, int } would give us alignment of 4, but
the original load from this type may have an alignment of 1 if packed.

Reviewed by David Majnemer

Differential revision: http://reviews.llvm.org/D17158
------------------------------------------------------------------------

Modified:
    llvm/branches/release_38/   (props changed)
    llvm/branches/release_38/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
    llvm/branches/release_38/test/Transforms/InstCombine/unpack-fca.ll

Propchange: llvm/branches/release_38/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Thu Feb 11 19:42:38 2016
@@ -1,3 +1,3 @@
 /llvm/branches/Apple/Pertwee:110850,110961
 /llvm/branches/type-system-rewrite:133420-134817
-/llvm/trunk:155241,257645,257648,257730,257775,257791,257875,257886,257902,257905,257925,257929-257930,257940,257942,257977,257979,257997,258168,258184,258207,258221,258273,258325,258406,258416,258428,258436,258471,258690,258729,258891,258971,259177-259178,259228,259236,259342,259346,259375,259381,259645,259649,259695-259696,259740,259798,259835,259840,259886,259888,259958
+/llvm/trunk:155241,257645,257648,257730,257775,257791,257875,257886,257902,257905,257925,257929-257930,257940,257942,257977,257979,257997,258168,258184,258207,258221,258273,258325,258406,258416,258428,258436,258471,258690,258729,258891,258971,259177-259178,259228,259236,259342,259346,259375,259381,259645,259649,259695-259696,259740,259798,259835,259840,259886,259888,259958,260587

Modified: llvm/branches/release_38/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_38/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp?rev=260640&r1=260639&r2=260640&view=diff
==============================================================================
--- llvm/branches/release_38/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp (original)
+++ llvm/branches/release_38/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp Thu Feb 11 19:42:38 2016
@@ -557,7 +557,8 @@ static Instruction *unpackLoadToAggregat
         ConstantInt::get(IdxType, i),
       };
       auto *Ptr = IC.Builder->CreateInBoundsGEP(ST, Addr, makeArrayRef(Indices), EltName);
-      auto *L = IC.Builder->CreateLoad(ST->getTypeAtIndex(i), Ptr, LoadName);
+      auto *L = IC.Builder->CreateAlignedLoad(Ptr, LI.getAlignment(),
+                                              LoadName);
       V = IC.Builder->CreateInsertValue(V, L, i);
     }
 

Modified: llvm/branches/release_38/test/Transforms/InstCombine/unpack-fca.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_38/test/Transforms/InstCombine/unpack-fca.ll?rev=260640&r1=260639&r2=260640&view=diff
==============================================================================
--- llvm/branches/release_38/test/Transforms/InstCombine/unpack-fca.ll (original)
+++ llvm/branches/release_38/test/Transforms/InstCombine/unpack-fca.ll Thu Feb 11 19:42:38 2016
@@ -136,3 +136,18 @@ define %B @structB(%B* %b.ptr) {
   %1 = load %B, %B* %b.ptr, align 8
   ret %B %1
 }
+
+%struct.S = type <{ i8, %struct.T }>
+%struct.T = type { i32, i32 }
+
+; Make sure that we do not increase alignment of packed struct element
+define i32 @packed_alignment(%struct.S* dereferenceable(9) %s) {
+; CHECK-LABEL: packed_alignment
+; CHECK-NEXT: %tv.elt1 = getelementptr inbounds %struct.S, %struct.S* %s, i64 0, i32 1, i32 1
+; CHECK-NEXT: %tv.unpack2 = load i32, i32* %tv.elt1, align 1
+; CHECK-NEXT: ret i32 %tv.unpack2
+  %t = getelementptr inbounds %struct.S, %struct.S* %s, i32 0, i32 1
+  %tv = load %struct.T, %struct.T* %t, align 1
+  %v = extractvalue %struct.T %tv, 1
+  ret i32 %v
+}