47 lines
1.7 KiB
C
47 lines
1.7 KiB
C
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// Location for variable "parama" optimized out.
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// Previously it would carry incorrect location
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// information in debug-info, see PR48719.
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// Now, the location is simply not emitted.
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// REQUIRES: lldb
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// UNSUPPORTED: system-windows
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// RUN: %clang -std=gnu11 -O3 -glldb %s -o %t
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// RUN: %dexter --fail-lt 0.1 -w --debugger lldb --binary %t -- %s
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// See NOTE at end for more info about the RUN command.
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// 1. SROA/mem2reg fully promotes parama.
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// 2. parama's value in the final block is the merge of values for it coming
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// out of entry and if.then. If the variable were used later in the function
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// mem2reg would insert a PHI here and add a dbg.value to track the merged
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// value in debug info. Because it is not used there is no PHI (the merged
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// value is implicit) and subsequently no dbg.value.
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// 3. SimplifyCFG later folds the blocks together (if.then does nothing besides
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// provide debug info so it is removed and if.end is folded into the entry
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// block).
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// The debug info is not updated to account for the implicit merged value prior
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// to (e.g. during mem2reg) or during SimplifyCFG so we end up seeing parama=5
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// for the entire function, which is incorrect.
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__attribute__((optnone))
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void fluff() {}
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__attribute__((noinline))
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int fun(int parama, int paramb) {
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if (parama)
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parama = paramb;
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fluff(); // DexLabel('s0')
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return paramb;
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}
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int main() {
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return fun(5, 20);
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}
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// DexExpectWatchValue('parama', 20, on_line=ref('s0'))
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//
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// NOTE: the dexter command uses --fail-lt 0.1 (instead of the standard 1.0)
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// because seeing 'optimized out' would still be a win; it's the best we can do
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// without using conditional DWARF operators in the location expression. Seeing
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// 'optimized out' should result in a score higher than 0.1.
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