[PATCH] D18746: [lanai] LanaiSetflagAluCombiner more conservative
Jacques Pienaar via llvm-commits
llvm-commits at lists.llvm.org
Sun Apr 3 09:50:48 PDT 2016
jpienaar created this revision.
jpienaar added a reviewer: eliben.
jpienaar added a subscriber: llvm-commits.
Herald added a subscriber: joker.eph.
LanaiSetflagAluCombiner could previously combine instructions across basic building blocks even when not legal. Make the LanaiSetflagAluCombiner more conservative to avoid this.
http://reviews.llvm.org/D18746
Files:
lib/Target/Lanai/LanaiSetflagAluCombiner.cpp
test/CodeGen/Lanai/combined_alu_setcc.ll
Index: test/CodeGen/Lanai/combined_alu_setcc.ll
===================================================================
--- test/CodeGen/Lanai/combined_alu_setcc.ll
+++ test/CodeGen/Lanai/combined_alu_setcc.ll
@@ -121,6 +121,50 @@
ret i32 %retval.0
}
; CHECK-LABEL: test4
-; CHECK: and.f
-; CHECK: and.f
-; CHECK: and.f
+; TODO: Re-enable test. This test is disabled post making the combiner more
+; conservative.
+; DISABLED_CHECK: and.f
+
+; Test to avoid incorrect fusing that spans across basic blocks
+ at a = global i32 -1, align 4
+ at b = global i32 0, align 4
+
+; Function Attrs: nounwind
+define void @testBB() {
+entry:
+ %0 = load i32, i32* @a, align 4, !tbaa !1
+ %1 = load i32, i32* @b, align 4, !tbaa !1
+ %sub.i = sub i32 %1, %0
+ %tobool = icmp sgt i32 %sub.i, -1
+ br i1 %tobool, label %if.end, label %if.then
+
+if.then: ; preds = %entry
+ %call1 = tail call i32 bitcast (i32 (...)* @g to i32 ()*)()
+ br label %while.body
+
+while.body: ; preds = %if.then, %while.body
+ br label %while.body
+
+if.end: ; preds = %entry
+ %cmp.i = icmp slt i32 %sub.i, 1
+ br i1 %cmp.i, label %if.then4, label %if.end7
+
+if.then4: ; preds = %if.end
+ %call5 = tail call i32 bitcast (i32 (...)* @g to i32 ()*)()
+ br label %while.body6
+
+while.body6: ; preds = %if.then4, %while.body6
+ br label %while.body6
+
+if.end7: ; preds = %if.end
+ ret void
+}
+
+declare i32 @g(...)
+; CHECK-LABEL: testBB
+; CHECK: sub.f {{.*}}, %r0
+
+!1 = !{!2, !2, i64 0}
+!2 = !{!"int", !3, i64 0}
+!3 = !{!"omnipotent char", !4, i64 0}
+!4 = !{!"Simple C/C++ TBAA"}
Index: lib/Target/Lanai/LanaiSetflagAluCombiner.cpp
===================================================================
--- lib/Target/Lanai/LanaiSetflagAluCombiner.cpp
+++ lib/Target/Lanai/LanaiSetflagAluCombiner.cpp
@@ -228,20 +228,22 @@
MbbIterator SCCUserIter = Instruction;
while (SCCUserIter != End) {
++SCCUserIter;
- // Early exit when encountering flag setting instruction.
- if (isFlagSettingInstruction(SCCUserIter->getOpcode()))
- break;
+ // Early exit when encountering flag setting or return instruction.
+ if (isFlagSettingInstruction(SCCUserIter->getOpcode()) ||
+ SCCUserIter->isReturn())
+ // Only return true if flags are set post the flag setting instruction
+ // tested or a return is executed.
+ return true;
int CCIndex = getCCOperandPosition(SCCUserIter->getOpcode());
if (CCIndex != -1) {
LPCC::CondCode CC = static_cast<LPCC::CondCode>(
SCCUserIter->getOperand(CCIndex).getImm());
+ // Return false if the flag is used outside of a EQ, NE, PL and MI.
if (CC != LPCC::ICC_EQ && CC != LPCC::ICC_NE && CC != LPCC::ICC_PL &&
CC != LPCC::ICC_MI)
return false;
}
}
-
- return true;
}
return false;
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