[SystemZ] Bugfix in adjustSubwordCmp.

Csmith generated a program where a store after load to the same address did
not get chained after the new load created during DAG legalizing, and so
performed an illegal overwrite of the expected value.

When the new zero-extending load is created, the chain users of the original
load must be updated, which was not done previously.

A similar case was also found and handled in lowerBITCAST.

Review: Ulrich Weigand
https://reviews.llvm.org/D40542

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319409 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/SystemZ/SystemZISelLowering.cpp b/lib/Target/SystemZ/SystemZISelLowering.cpp
index d49d7316e682b3acca2ae54cb7aef6407fa75f2c..ad14e5e34e2ec3ede7bb1b8c7025f5f83f4ea688 100644 (file)
--- a/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -1844,11 +1844,14 @@ static void adjustSubwordCmp(SelectionDAG &DAG, const SDLoc &DL,
                               ISD::SEXTLOAD :
                               ISD::ZEXTLOAD);
   if (C.Op0.getValueType() != MVT::i32 ||
-      Load->getExtensionType() != ExtType)
+      Load->getExtensionType() != ExtType) {
     C.Op0 = DAG.getExtLoad(ExtType, SDLoc(Load), MVT::i32, Load->getChain(),
                            Load->getBasePtr(), Load->getPointerInfo(),
                            Load->getMemoryVT(), Load->getAlignment(),
                            Load->getMemOperand()->getFlags());
+    // Update the chain uses.
+    DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 1), C.Op0.getValue(1));
+  }
 
   // Make sure that the second operand is an i32 with the right value.
   if (C.Op1.getValueType() != MVT::i32 ||
@@ -2940,9 +2943,13 @@ SDValue SystemZTargetLowering::lowerBITCAST(SDValue Op,
   // but we need this case for bitcasts that are created during lowering
   // and which are then lowered themselves.
   if (auto *LoadN = dyn_cast<LoadSDNode>(In))
-    if (ISD::isNormalLoad(LoadN))
-      return DAG.getLoad(ResVT, DL, LoadN->getChain(), LoadN->getBasePtr(),
-                         LoadN->getMemOperand());
+    if (ISD::isNormalLoad(LoadN)) {
+      SDValue NewLoad = DAG.getLoad(ResVT, DL, LoadN->getChain(),
+                                    LoadN->getBasePtr(), LoadN->getMemOperand());
+      // Update the chain uses.
+      DAG.ReplaceAllUsesOfValueWith(SDValue(LoadN, 1), NewLoad.getValue(1));
+      return NewLoad;
+    }
 
   if (InVT == MVT::i32 && ResVT == MVT::f32) {
     SDValue In64;

diff --git a/test/CodeGen/SystemZ/dag-combine-02.ll b/test/CodeGen/SystemZ/dag-combine-02.ll
new file mode 100644 (file)
index 0000000..b20133f
--- /dev/null
+++ b/test/CodeGen/SystemZ/dag-combine-02.ll
@@ -0,0 +1,192 @@
+; Test that adjustSubwordCmp() maintains the chains properly when creating a
+; new extending load.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 -O3 | FileCheck %s
+
+@g_56 = external hidden unnamed_addr global i64, align 8
+@func_22.l_91 = external hidden unnamed_addr constant [4 x [7 x i16*]], align 8
+@g_102 = external hidden unnamed_addr global i16**, align 8
+@.str = external hidden unnamed_addr constant [2 x i8], align 2
+@.str.1 = external hidden unnamed_addr constant [15 x i8], align 2
+@crc32_context = external hidden unnamed_addr global i32, align 4
+@crc32_tab = external hidden unnamed_addr global [256 x i32], align 4
+@.str.2 = external hidden unnamed_addr constant [36 x i8], align 2
+@.str.3 = external hidden unnamed_addr constant [15 x i8], align 2
+@g_181.0.4.5 = external hidden unnamed_addr global i1, align 2
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #0
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1) #0
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #0
+
+; Function Attrs: nounwind
+define signext i32 @main(i32 signext, i8** nocapture readonly) local_unnamed_addr #1 {
+  %3 = alloca [4 x [7 x i16*]], align 8
+  %4 = icmp eq i32 %0, 2
+  br i1 %4, label %5, label %11
+
+; <label>:5:                                      ; preds = %2
+  %6 = getelementptr inbounds i8*, i8** %1, i64 1
+  %7 = load i8*, i8** %6, align 8
+  %8 = tail call signext i32 @strcmp(i8* %7, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0)) #4
+  %9 = icmp eq i32 %8, 0
+  %10 = zext i1 %9 to i32
+  br label %11
+
+; <label>:11:                                     ; preds = %5, %2
+  %12 = phi i32 [ 0, %2 ], [ %10, %5 ]
+  br label %13
+
+; <label>:13:                                     ; preds = %13, %11
+  %14 = phi i64 [ 0, %11 ], [ %58, %13 ]
+  %15 = phi <4 x i32> [ <i32 0, i32 1, i32 2, i32 3>, %11 ], [ %59, %13 ]
+  %16 = and <4 x i32> %15, <i32 1, i32 1, i32 1, i32 1>
+  %17 = icmp eq <4 x i32> %16, zeroinitializer
+  %18 = lshr <4 x i32> %15, <i32 1, i32 1, i32 1, i32 1>
+  %19 = xor <4 x i32> %18, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %20 = select <4 x i1> %17, <4 x i32> %18, <4 x i32> %19
+  %21 = and <4 x i32> %20, <i32 1, i32 1, i32 1, i32 1>
+  %22 = icmp eq <4 x i32> %21, zeroinitializer
+  %23 = lshr <4 x i32> %20, <i32 1, i32 1, i32 1, i32 1>
+  %24 = xor <4 x i32> %23, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %25 = select <4 x i1> %22, <4 x i32> %23, <4 x i32> %24
+  %26 = and <4 x i32> %25, <i32 1, i32 1, i32 1, i32 1>
+  %27 = icmp eq <4 x i32> %26, zeroinitializer
+  %28 = lshr <4 x i32> %25, <i32 1, i32 1, i32 1, i32 1>
+  %29 = xor <4 x i32> %28, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %30 = select <4 x i1> %27, <4 x i32> %28, <4 x i32> %29
+  %31 = and <4 x i32> %30, <i32 1, i32 1, i32 1, i32 1>
+  %32 = icmp eq <4 x i32> %31, zeroinitializer
+  %33 = lshr <4 x i32> %30, <i32 1, i32 1, i32 1, i32 1>
+  %34 = xor <4 x i32> %33, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %35 = select <4 x i1> %32, <4 x i32> %33, <4 x i32> %34
+  %36 = and <4 x i32> %35, <i32 1, i32 1, i32 1, i32 1>
+  %37 = icmp eq <4 x i32> %36, zeroinitializer
+  %38 = lshr <4 x i32> %35, <i32 1, i32 1, i32 1, i32 1>
+  %39 = xor <4 x i32> %38, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %40 = select <4 x i1> %37, <4 x i32> %38, <4 x i32> %39
+  %41 = and <4 x i32> %40, <i32 1, i32 1, i32 1, i32 1>
+  %42 = icmp eq <4 x i32> %41, zeroinitializer
+  %43 = lshr <4 x i32> %40, <i32 1, i32 1, i32 1, i32 1>
+  %44 = xor <4 x i32> %43, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %45 = select <4 x i1> %42, <4 x i32> %43, <4 x i32> %44
+  %46 = and <4 x i32> %45, <i32 1, i32 1, i32 1, i32 1>
+  %47 = icmp eq <4 x i32> %46, zeroinitializer
+  %48 = lshr <4 x i32> %45, <i32 1, i32 1, i32 1, i32 1>
+  %49 = xor <4 x i32> %48, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %50 = select <4 x i1> %47, <4 x i32> %48, <4 x i32> %49
+  %51 = and <4 x i32> %50, <i32 1, i32 1, i32 1, i32 1>
+  %52 = icmp eq <4 x i32> %51, zeroinitializer
+  %53 = lshr <4 x i32> %50, <i32 1, i32 1, i32 1, i32 1>
+  %54 = xor <4 x i32> %53, <i32 -306674912, i32 -306674912, i32 -306674912, i32 -306674912>
+  %55 = select <4 x i1> %52, <4 x i32> %53, <4 x i32> %54
+  %56 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %14
+  %57 = bitcast i32* %56 to <4 x i32>*
+  store <4 x i32> %55, <4 x i32>* %57, align 4
+  %58 = add i64 %14, 4
+  %59 = add <4 x i32> %15, <i32 4, i32 4, i32 4, i32 4>
+  %60 = icmp eq i64 %58, 256
+  br i1 %60, label %61, label %13
+
+; <label>:61:                                     ; preds = %13
+; CHECK-LABEL: BB#6:
+; CHECK: stgrl   %r1, g_56
+; CHECK: llhrl   %r1, g_56+6
+; CHECK: stgrl   %r2, g_56
+  store i64 0, i64* @g_56, align 8
+  %62 = bitcast [4 x [7 x i16*]]* %3 to i8*
+  call void @llvm.lifetime.start.p0i8(i64 224, i8* nonnull %62) #5
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull %62, i8* bitcast ([4 x [7 x i16*]]* @func_22.l_91 to i8*), i64 224, i32 8, i1 false) #5
+  %63 = getelementptr inbounds [4 x [7 x i16*]], [4 x [7 x i16*]]* %3, i64 0, i64 0, i64 2
+  store i16** %63, i16*** @g_102, align 8
+  %64 = load i64, i64* @g_56, align 8
+  store i64 2, i64* @g_56, align 8
+  %65 = and i64 %64, 65535
+  %66 = icmp eq i64 %65, 0
+  br i1 %66, label %68, label %67
+
+; <label>:67:                                     ; preds = %61
+  store i1 true, i1* @g_181.0.4.5, align 2
+  br label %68
+
+; <label>:68:                                     ; preds = %67, %61
+  call void @llvm.lifetime.end.p0i8(i64 224, i8* nonnull %62) #5
+  %69 = load i1, i1* @g_181.0.4.5, align 2
+  %70 = select i1 %69, i32 0, i32 72
+  %71 = load i32, i32* @crc32_context, align 4
+  %72 = lshr i32 %71, 8
+  %73 = and i32 %71, 255
+  %74 = xor i32 %73, %70
+  %75 = zext i32 %74 to i64
+  %76 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %75
+  %77 = load i32, i32* %76, align 4
+  %78 = xor i32 %72, %77
+  %79 = lshr i32 %78, 8
+  %80 = and i32 %78, 255
+  %81 = zext i32 %80 to i64
+  %82 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %81
+  %83 = load i32, i32* %82, align 4
+  %84 = xor i32 %79, %83
+  %85 = lshr i32 %84, 8
+  %86 = and i32 %84, 255
+  %87 = zext i32 %86 to i64
+  %88 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %87
+  %89 = load i32, i32* %88, align 4
+  %90 = xor i32 %85, %89
+  %91 = lshr i32 %90, 8
+  %92 = and i32 %90, 255
+  %93 = zext i32 %92 to i64
+  %94 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %93
+  %95 = load i32, i32* %94, align 4
+  %96 = xor i32 %91, %95
+  %97 = lshr i32 %96, 8
+  %98 = and i32 %96, 255
+  %99 = zext i32 %98 to i64
+  %100 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %99
+  %101 = load i32, i32* %100, align 4
+  %102 = xor i32 %97, %101
+  %103 = lshr i32 %102, 8
+  %104 = and i32 %102, 255
+  %105 = zext i32 %104 to i64
+  %106 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %105
+  %107 = load i32, i32* %106, align 4
+  %108 = xor i32 %103, %107
+  %109 = lshr i32 %108, 8
+  %110 = and i32 %108, 255
+  %111 = zext i32 %110 to i64
+  %112 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %111
+  %113 = load i32, i32* %112, align 4
+  %114 = xor i32 %109, %113
+  %115 = lshr i32 %114, 8
+  %116 = and i32 %114, 255
+  %117 = zext i32 %116 to i64
+  %118 = getelementptr inbounds [256 x i32], [256 x i32]* @crc32_tab, i64 0, i64 %117
+  %119 = load i32, i32* %118, align 4
+  %120 = xor i32 %115, %119
+  store i32 %120, i32* @crc32_context, align 4
+  %121 = icmp eq i32 %12, 0
+  br i1 %121, label %127, label %122
+
+; <label>:122:                                    ; preds = %68
+  %123 = xor i32 %120, -1
+  %124 = zext i32 %123 to i64
+  %125 = call signext i32 (i8*, ...) @printf(i8* getelementptr inbounds ([36 x i8], [36 x i8]* @.str.2, i64 0, i64 0), i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.1, i64 0, i64 0), i64 %124) #5
+  %126 = load i32, i32* @crc32_context, align 4
+  br label %127
+
+; <label>:127:                                    ; preds = %122, %68
+  %128 = phi i32 [ %120, %68 ], [ %126, %122 ]
+  %129 = xor i32 %128, -1
+  %130 = call signext i32 (i8*, ...) @printf(i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.3, i64 0, i64 0), i32 zeroext %129) #5
+  ret i32 0
+}
+
+; Function Attrs: nounwind readonly
+declare signext i32 @strcmp(i8* nocapture, i8* nocapture) local_unnamed_addr #2
+
+; Function Attrs: nounwind
+declare signext i32 @printf(i8* nocapture readonly, ...) local_unnamed_addr #3