R600: Fix a crash in the AMDILCFGStructurizer
We were calling llvm_unreachable() when failing to optimize the
branch into if case. However, it is still possible for us
to structurize the CFG by duplicating blocks even if this optimization
fails.
Reviewed-by: Vincent Lejeune<vljn at ovi.com>
llvm-svn: 192813
diff --git a/llvm/test/CodeGen/R600/structurize.ll b/llvm/test/CodeGen/R600/structurize.ll
new file mode 100644
index 0000000..b955619
--- /dev/null
+++ b/llvm/test/CodeGen/R600/structurize.ll
@@ -0,0 +1,83 @@
+; RUN: llc < %s -march=r600 -mcpu=redwood | FileCheck %s
+; Test case for a crash in the AMDILCFGStructurizer from a CFG like this:
+;
+; entry
+; / \
+; diamond_head branch_from
+; / \ |
+; diamond_false diamond_true
+; \ /
+; done
+;
+; When the diamond_true branch had more than 100 instructions.
+;
+;
+
+; CHECK-LABEL: @branch_into_diamond
+; === entry block:
+; CHECK: ALU_PUSH_BEFORE
+; === Branch instruction (IF):
+; CHECK: JUMP
+ ; === branch_from block
+ ; CHECK: ALU
+ ; === Duplicated diamond_true block (There can be more than one ALU clause):
+ ; === XXX: We should be able to optimize this so the basic block is not
+ ; === duplicated. See comments in
+ ; === AMDGPUCFGStructurizer::improveSimpleJumpintoIf()
+ ; CHECK: ALU
+; === Branch instruction (ELSE):
+; CHECK: ELSE
+ ; === diamond_head block:
+ ; CHECK: ALU_PUSH_BEFORE
+ ; === Branch instruction (IF):
+ ; CHECK: JUMP
+ ; === diamond_true block (There can be more than one ALU clause):
+ ; ALU
+ ; === Branch instruction (ELSE):
+ ; CHECK: ELSE
+ ; === diamond_false block plus implicit ENDIF
+ ; CHECK: ALU_POP_AFTER
+; === Branch instruction (ENDIF):
+; CHECK: POP
+; === done block:
+; CHECK: ALU
+; CHECK: MEM_RAT_CACHELESS
+; CHECK: CF_END
+
+
+define void @branch_into_diamond(i32 addrspace(1)* %out, i32 %a, i32 %b, i32 %c) {
+entry:
+%0 = icmp ne i32 %a, 0
+ br i1 %0, label %diamond_head, label %branch_from
+
+diamond_head:
+ %1 = icmp ne i32 %a, 1
+ br i1 %1, label %diamond_true, label %diamond_false
+
+branch_from:
+ %2 = add i32 %a, 1
+ br label %diamond_true
+
+diamond_false:
+ %3 = add i32 %a, 2
+ br label %done
+
+diamond_true:
+ %4 = phi i32 [%2, %branch_from], [%a, %diamond_head]
+ ; This block needs to be > 100 ISA instructions to hit the bug,
+ ; so we'll use udiv instructions.
+ %div0 = udiv i32 %a, %b
+ %div1 = udiv i32 %div0, %4
+ %div2 = udiv i32 %div1, 11
+ %div3 = udiv i32 %div2, %a
+ %div4 = udiv i32 %div3, %b
+ %div5 = udiv i32 %div4, %c
+ %div6 = udiv i32 %div5, %div0
+ %div7 = udiv i32 %div6, %div1
+ br label %done
+
+done:
+ %5 = phi i32 [%3, %diamond_false], [%div7, %diamond_true]
+ store i32 %5, i32 addrspace(1)* %out
+ ret void
+}