MachineInstr *CondDef = MRI.getVRegDef(I.getOperand(1).getReg());
while (CondDef) {
// We can only fold if all of the defs have one use.
- if (!MRI.hasOneUse(CondDef->getOperand(0).getReg()))
- return false;
+ Register CondDefReg = CondDef->getOperand(0).getReg();
+ if (!MRI.hasOneUse(CondDefReg)) {
+ // Unless it's another select.
+ for (auto UI = MRI.use_instr_begin(CondDefReg), UE = MRI.use_instr_end();
+ UI != UE; ++UI) {
+ if (CondDef == &*UI)
+ continue;
+ if (UI->getOpcode() != TargetOpcode::G_SELECT)
+ return false;
+ }
+ }
// We can skip over G_TRUNC since the condition is 1-bit.
// Truncating/extending can have no impact on the value.
# Verify the following:
#
# - We can fold compares into selects.
-# - This only happens when the result of the compare is only used by the select.
+# - This only happens when the result of the compare is only used by selects.
#
# Also verify that, for now:
#
...
---
+name: fcmp_more_than_one_select
+alignment: 4
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $s0, $s1, $w1
+
+ ; CHECK-LABEL: name: fcmp_more_than_one_select
+ ; CHECK: liveins: $s0, $s1, $w1
+ ; CHECK: [[COPY:%[0-9]+]]:fpr32 = COPY $s0
+ ; CHECK: [[COPY1:%[0-9]+]]:fpr32 = COPY $s1
+ ; CHECK: [[FMOVS0_:%[0-9]+]]:fpr32 = FMOVS0
+ ; CHECK: FCMPSri [[COPY]], implicit-def $nzcv
+ ; CHECK: [[FCSELSrrr:%[0-9]+]]:fpr32 = FCSELSrrr [[FMOVS0_]], [[COPY1]], 0, implicit $nzcv
+ ; CHECK: FCMPSri [[COPY]], implicit-def $nzcv
+ ; CHECK: [[FCSELSrrr1:%[0-9]+]]:fpr32 = FCSELSrrr [[COPY1]], [[FMOVS0_]], 0, implicit $nzcv
+ ; CHECK: $s0 = COPY [[FCSELSrrr]]
+ ; CHECK: $s1 = COPY [[FCSELSrrr1]]
+ ; CHECK: RET_ReallyLR implicit $s0
+ %0:fpr(s32) = COPY $s0
+ %1:fpr(s32) = COPY $s1
+ %2:fpr(s32) = G_FCONSTANT float 0.000000e+00
+ %5:gpr(s32) = G_FCMP floatpred(oeq), %0(s32), %2
+ %3:gpr(s1) = G_TRUNC %5(s32)
+ %6:fpr(s1) = COPY %3(s1)
+ %4:fpr(s32) = G_SELECT %6(s1), %2, %1
+ %7:fpr(s32) = G_SELECT %6(s1), %1, %2
+ $s0 = COPY %4(s32)
+ $s1 = COPY %7(s32)
+ RET_ReallyLR implicit $s0
+
+...
+---
name: using_icmp
alignment: 4
legalized: true