[SystemZ] Be more careful about inverting CC masks
System z branches have a mask to select which of the 4 CC values should
cause the branch to be taken. We can invert a branch by inverting the mask.
However, not all instructions can produce all 4 CC values, so inverting
the branch like this can lead to some oddities. For example, integer
comparisons only produce a CC of 0 (equal), 1 (less) or 2 (greater).
If an integer EQ is reversed to NE before instruction selection,
the branch will test for 1 or 2. If instead the branch is reversed
after instruction selection (by inverting the mask), it will test for
1, 2 or 3. Both are correct, but the second isn't really canonical.
This patch therefore keeps track of which CC values are possible
and uses this when inverting a mask.
Although this is mostly cosmestic, it fixes undefined behavior
for the CIJNLH in branch-08.ll. Another fix would have been
to mask out bit 0 when generating the fused compare and branch,
but the point of this patch is that we shouldn't need to do that
in the first place.
The patch also makes it easier to reuse CC results from other instructions.
llvm-svn: 187495
diff --git a/llvm/lib/Target/SystemZ/SystemZ.h b/llvm/lib/Target/SystemZ/SystemZ.h
index 24612bb..4c1e81a0 100644
--- a/llvm/lib/Target/SystemZ/SystemZ.h
+++ b/llvm/lib/Target/SystemZ/SystemZ.h
@@ -30,16 +30,28 @@
const unsigned CCMASK_3 = 1 << 0;
const unsigned CCMASK_ANY = CCMASK_0 | CCMASK_1 | CCMASK_2 | CCMASK_3;
- // Condition-code mask assignments for floating-point comparisons.
+ // Condition-code mask assignments for integer and floating-point
+ // comparisons.
const unsigned CCMASK_CMP_EQ = CCMASK_0;
const unsigned CCMASK_CMP_LT = CCMASK_1;
const unsigned CCMASK_CMP_GT = CCMASK_2;
- const unsigned CCMASK_CMP_UO = CCMASK_3;
const unsigned CCMASK_CMP_NE = CCMASK_CMP_LT | CCMASK_CMP_GT;
const unsigned CCMASK_CMP_LE = CCMASK_CMP_EQ | CCMASK_CMP_LT;
const unsigned CCMASK_CMP_GE = CCMASK_CMP_EQ | CCMASK_CMP_GT;
+
+ // Condition-code mask assignments for floating-point comparisons only.
+ const unsigned CCMASK_CMP_UO = CCMASK_3;
const unsigned CCMASK_CMP_O = CCMASK_ANY ^ CCMASK_CMP_UO;
+ // All condition-code values produced by comparisons.
+ const unsigned CCMASK_ICMP = CCMASK_0 | CCMASK_1 | CCMASK_2;
+ const unsigned CCMASK_FCMP = CCMASK_0 | CCMASK_1 | CCMASK_2 | CCMASK_3;
+
+ // Condition-code mask assignments for CS.
+ const unsigned CCMASK_CS_EQ = CCMASK_0;
+ const unsigned CCMASK_CS_NE = CCMASK_1;
+ const unsigned CCMASK_CS = CCMASK_0 | CCMASK_1;
+
// Return true if Val fits an LLILL operand.
static inline bool isImmLL(uint64_t Val) {
return (Val & ~0x000000000000ffffULL) == 0;