Don't form PPC CTR loops for over-sized exit counts
Although you can't generate this from C on PPC64, if you have a loop using a
64-bit counter on PPC32 then you can't form a CTR-based loop for it. This had
been cauing the PPCCTRLoops pass to assert.
Thanks to Joerg Sonnenberger for providing a test case!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185361 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCCTRLoops.cpp b/lib/Target/PowerPC/PPCCTRLoops.cpp
index 08247c2..bfc9495 100644
--- a/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/lib/Target/PowerPC/PPCCTRLoops.cpp
@@ -415,6 +415,9 @@
} else if (!SE->isLoopInvariant(EC, L))
continue;
+ if (SE->getTypeSizeInBits(EC->getType()) > (TT.isArch64Bit() ? 64 : 32))
+ continue;
+
// We now have a loop-invariant count of loop iterations (which is not the
// constant zero) for which we know that this loop will not exit via this
// exisiting block.
diff --git a/test/CodeGen/PowerPC/ctrloop-large-ec.ll b/test/CodeGen/PowerPC/ctrloop-large-ec.ll
new file mode 100644
index 0000000..c18bdab
--- /dev/null
+++ b/test/CodeGen/PowerPC/ctrloop-large-ec.ll
@@ -0,0 +1,23 @@
+; RUN: llc -mcpu=ppc32 < %s
+target datalayout = "E-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v128:128:128-n32"
+target triple = "powerpc-unknown-linux-gnu"
+
+define void @fn1() {
+entry:
+ br i1 undef, label %for.end, label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %inc3 = phi i64 [ %inc, %for.body ], [ undef, %entry ]
+ %inc = add nsw i64 %inc3, 1
+ %tobool = icmp eq i64 %inc, 0
+ br i1 %tobool, label %for.end, label %for.body
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+; On PPC32, CTR is also 32 bits, and so cannot hold a 64-bit count.
+; CHECK: @fn1
+; CHECK-NOT: mtctr
+; CHECK: blr
+