PPCDAGToDAGISel::isRunOfOnes should return false on zero

This fixes a bug (found by csmith) at -O0 where we attempt to create a RLWIMI
with an out-of-range operand. Most uses of the isRunOfOnes function are guarded
by a condition that the value is not zero. This was not true in two places, and
in both places a zero input would result in an out-of-rage MB value (= 32).

To fix this, isRunOfOnes returns false on a zero input (and I've remove one
now-redundant guard).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186101 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 901d3690972c7b9d49ee0f9e875dc1cb3eb73df4..475bde18efb7ac92445cf45f51fb89e276b72224 100644 (file)
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -330,6 +330,9 @@ static bool isOpcWithIntImmediate(SDNode *N, unsigned Opc, unsigned& Imm) {
 }
 
 bool PPCDAGToDAGISel::isRunOfOnes(unsigned Val, unsigned &MB, unsigned &ME) {
+  if (!Val)
+    return false;
+
   if (isShiftedMask_32(Val)) {
     // look for the first non-zero bit
     MB = countLeadingZeros(Val);
@@ -435,7 +438,7 @@ SDNode *PPCDAGToDAGISel::SelectBitfieldInsert(SDNode *N) {
     }
 
     unsigned MB, ME;
-    if (InsertMask && isRunOfOnes(InsertMask, MB, ME)) {
+    if (isRunOfOnes(InsertMask, MB, ME)) {
       SDValue Tmp1, Tmp2;
 
       if ((Op1Opc == ISD::SHL || Op1Opc == ISD::SRL) &&

diff --git a/test/CodeGen/PowerPC/zero-not-run.ll b/test/CodeGen/PowerPC/zero-not-run.ll
new file mode 100644 (file)
index 0000000..04c4277
--- /dev/null
+++ b/test/CodeGen/PowerPC/zero-not-run.ll
@@ -0,0 +1,27 @@
+; RUN: llc -O0 -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 < %s
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+; Function Attrs: nounwind
+define internal i32* @func_65(i32* %p_66) #0 {
+entry:
+  br i1 undef, label %for.body, label %for.end731
+
+for.body:                                         ; preds = %entry
+  %0 = load i32* undef, align 4
+  %or31 = or i32 %0, 319143828
+  store i32 %or31, i32* undef, align 4
+  %cmp32 = icmp eq i32 319143828, %or31
+  %conv33 = zext i1 %cmp32 to i32
+  %conv34 = sext i32 %conv33 to i64
+  %call35 = call i64 @safe_mod_func_uint64_t_u_u(i64 %conv34, i64 -10)
+  unreachable
+
+for.end731:                                       ; preds = %entry
+  ret i32* undef
+}
+
+; Function Attrs: nounwind
+declare i64 @safe_mod_func_uint64_t_u_u(i64, i64) #0
+
+attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }